Update mongoengine to 0.20.0

[pyup-bot]

This PR updates mongoengine from 0.16.3 to 0.20.0.

Changelog

0.20.0

=================
- ATTENTION: Drop support for Python2
- Add Mongo 4.0 to Travis
- Fix error when setting a string as a ComplexDateTimeField 2253
- Bump development Status classifier to Production/Stable 2232
- Improve Queryset.get to avoid confusing MultipleObjectsReturned message in case multiple match are found 630
- Fixed a bug causing inaccurate query results, while combining ``__raw__`` and regular filters for the same field 2264
- Add support for the `elemMatch` projection operator in .fields() (e.g BlogPost.objects.fields(elemMatch__comments="test")) 2267
- DictField validate failed without default connection (bug introduced in 0.19.0) 2239
- Remove methods that were deprecated years ago:
 - name parameter in Field constructor e.g `StringField(name="...")`, was replaced by db_field
 - Queryset.slave_okay() was deprecated since pymongo3
 - dropDups was dropped with MongoDB3
 - ``Queryset._ensure_indexes`` and ``Queryset.ensure_indexes``, the right method to use is ``Document.ensure_indexes``
- Added pre-commit for development/CI 2212
- Renamed requirements-lint.txt to requirements-dev.txt 2212
- Support for setting ReadConcern 2255

0.19.1

=================
- Requires Pillow < 7.0.0 as it dropped Python2 support
- DEPRECATION: The interface of ``QuerySet.aggregate`` method was changed, it no longer takes an unpacked list of
 pipeline steps (*pipeline) but simply takes the pipeline list just like ``pymongo.Collection.aggregate`` does. 2079

0.19.0

=================
- BREAKING CHANGE: ``class_check`` and ``read_preference`` keyword arguments are no longer available when filtering a ``QuerySet``. 2112
 - Instead of ``Doc.objects(foo=bar, read_preference=...)`` use ``Doc.objects(foo=bar).read_preference(...)``.
 - Instead of ``Doc.objects(foo=bar, class_check=False)`` use ``Doc.objects(foo=bar).clear_cls_query(...)``.
 - This change also renames the private ``QuerySet._initial_query`` attribute to ``_cls_query``.
- BREAKING CHANGE: Removed the deprecated ``format`` param from ``QuerySet.explain``. 2113
- BREAKING CHANGE: Renamed ``MongoEngineConnectionError`` to ``ConnectionFailure``. 2111
 - If you catch/use ``MongoEngineConnectionError`` in your code, you'll have to rename it.
- BREAKING CHANGE: Positional arguments when instantiating a document are no longer supported. 2103
 - From now on keyword arguments (e.g. ``Doc(field_name=value)``) are required.
- BREAKING CHANGE: A ``LazyReferenceField`` is now stored in the ``_data`` field of its parent as a ``DBRef``, ``Document``, or ``EmbeddedDocument`` (``ObjectId`` is no longer allowed). 2182
- DEPRECATION: ``Q.empty`` & ``QNode.empty`` are marked as deprecated and will be removed in a next version of MongoEngine. 2210
 - Added ability to check if Q or QNode are empty by parsing them to bool.
 - Instead of ``Q(name="John").empty`` use ``not Q(name="John")``.
- Fix updating/modifying/deleting/reloading a document that's sharded by a field with ``db_field`` specified. 2125
- Only set no_cursor_timeout when requested (fixes an incompatibility with MongoDB 4.2) 2148
- ``ListField`` now accepts an optional ``max_length`` parameter. 2110
- Improve error message related to InvalidDocumentError 2180
- Added BulkWriteError to replace NotUniqueError which was misleading in bulk write insert 2152
- Added ability to compare Q and Q operations 2204
- Added ability to use a db alias on query_counter 2194
- Added ability to specify collations for querysets with ``Doc.objects.collation`` 2024
- Fix updates of a list field by negative index 2094
- Switch from nosetest to pytest as test runner 2114
- The codebase is now formatted using ``black``. 2109
- Documentation improvements:
 - Documented how `pymongo.monitoring` can be used to log all queries issued by MongoEngine to the driver.

0.18.2

=================
- Replace deprecated PyMongo v2.x methods with their v3.x equivalents in the ``SequenceField``. 2097
- Various code clarity and documentation improvements.

0.18.1

=================
- Fix a bug introduced in 0.18.0 which was causing ``Document.save`` to update all the fields instead of updating only the modified fields. This bug only occurred when using a custom PK. 2082
- Add Python 3.7 to Travis CI. 2058

0.18.0

=================
- Drop support for EOL'd MongoDB v2.6, v3.0, and v3.2.
- MongoEngine now requires PyMongo >= v3.4. Travis CI now tests against MongoDB v3.4 – v3.6 and PyMongo v3.4 – v3.6. 2017 2066
- Improve performance by avoiding a call to ``to_mongo`` in ``Document.save``. 2049
- Connection/disconnection improvements:
 - Expose ``mongoengine.connection.disconnect`` and ``mongoengine.connection.disconnect_all``.
 - Fix disconnecting. 566 1599 605 607 1213 565
 - Improve documentation of ``connect``/``disconnect``.
 - Fix issue when using multiple connections to the same mongo with different credentials. 2047
 - ``connect`` fails immediately when db name contains invalid characters. 2031 1718
- Fix the default write concern of ``Document.save`` that was overwriting the connection write concern. 568
- Fix querying on ``List(EmbeddedDocument)`` subclasses fields. 1961 1492
- Fix querying on ``(Generic)EmbeddedDocument`` subclasses fields. 475
- Fix ``QuerySet.aggregate`` so that it takes limit and skip value into account. 2029
- Generate unique indices for ``SortedListField`` and ``EmbeddedDocumentListFields``. 2020
- BREAKING CHANGE: Changed the behavior of a custom field validator (i.e ``validation`` parameter of a ``Field``). It is now expected to raise a ``ValidationError`` instead of returning ``True``/``False``. 2050
- BREAKING CHANGES (associated with connection/disconnection fixes):
 - Calling ``connect`` 2 times with the same alias and different parameter will raise an error (should call ``disconnect`` first).
 - ``disconnect`` now clears ``mongoengine.connection._connection_settings``.
 - ``disconnect`` now clears the cached attribute ``Document._collection``.
- BREAKING CHANGE: ``EmbeddedDocument.save`` & ``.reload`` no longer exist. 1552

0.17.0

=================
- POTENTIAL BREAKING CHANGE: All result fields are now passed, including internal fields (``_cls``, ``_id``) when using ``QuerySet.as_pymongo``. 1976
- Document a BREAKING CHANGE introduced in 0.15.3 and not reported at that time. 1995
- DEPRECATION: ``EmbeddedDocument.save`` & ``.reload`` are marked as deprecated and will be removed in a next version of MongoEngine. 1552
- Fix ``QuerySet.only`` working improperly after using ``QuerySet.count`` of the same instance of a ``QuerySet``.
- Fix ``batch_size`` that was not copied when cloning a ``QuerySet`` object. 2011
- Fix ``InvalidStringData`` error when using ``modify`` on a ``BinaryField``. 1127
- Fix test suite and CI to support MongoDB v3.4. 1445
- Fix reference fields querying the database on each access if value contains orphan DBRefs.

Links

• PyPI: https://pypi.org/project/mongoengine
• Changelog: https://pyup.io/changelogs/mongoengine/
• Repo: https://github.com/MongoEngine/mongoengine/tarball/master
• Homepage: http://mongoengine.org/

[pyup-bot]

Closing this in favor of #593