Making the library ready for Python 3.7, 3.8, 3.9 and 3.10

[dprada]

Python 3.7 expires in 11 months (27 Jun 2023). So, it is probably time to prepare PyUnitWizard for later Python versions (3.8, 3.9, and 3.10). Another good reason to do it is that newer versions are faster.

Although the typical suggestion is to give support to the last three Python versions, from now on we will try to keep the library available for every supported version: 3.7, 3.8, 3.9, and 3.10 (at the current moment).

[dprada]

Some tests fail due to different reasons.

Tests with Python 3.7 fail

There is a SyntaxisError in unyt with Python 3.7. Let's see if this is solved in the future. At this point let's take the following actions:

• we will skip tests with Python 3.7.
• since unyt is a suggested but not required package, we won't cancel the building of conda packages for Python 3.7

Test with Python 3.10 and macos-latest fails

There is a problem with openmm in this case:

Encountered problems while solving:
    - package openmm-7.6.0-py36he516fd0_0_apple requires python >=3.6,<3.7.0a0, but none of the providers can be installed

At this point let's take the following actions:

• Let's cancel provisionally this test.
• since openmm is a suggested but not required package, we won't cancel the building of conda package in this case

All tests with windows-latest fail

There is an error with openmm and windows:

_______________ ERROR collecting pyunitwizard/tests/test_get.py _______________
pyunitwizard\forms\api_openmm_unit.py:6: in <module>
    import openmm.unit as openmm_unit
C:\Miniconda\envs\test\lib\site-packages\openmm\__init__.py:19: in <module>
    from openmm.openmm import *
C:\Miniconda\envs\test\lib\site-packages\openmm\openmm.py:13: in <module>
    from . import _openmm
E   ImportError: DLL load failed while importing _openmm: The specified module could not be found.

At this point let's take the following actions:

• Let's cancel provisionally this test.
• since openmm is a suggested but not required package, we won't cancel the building of conda package in this case

[dprada]

Error building packages with Python 3.10

There is an error building packages with Python 3.10.:

  ValueError: Incompatible component merge:
    - 'mpi_mpich_*'
    - 'mpi_mpich_tempest*'
  Error: Process completed with exit code 1.

The error was already reported in conda/conda#11442.

[dprada]

Some tests fail due to different reasons.

Tests with Python 3.7 fail

There is a SyntaxisError in unyt with Python 3.7. Let's see if this is solved in the future. At this point let's take the following actions:

• we will skip tests with Python 3.7.
• since unyt is a suggested but not required package, we won't cancel the building of conda packages for Python 3.7

Unyt is not longer supported for Python 3.7. We need to implement a mechanism to skip tests with unyt with this Python version.