Bump environs from 8.0.0 to 9.0.0 in /requirements

[dependabot]

Bumps environs from 8.0.0 to 9.0.0.

Changelog

Sourced from environs's changelog.

9.0.0 (2020-10-31)

• Backwards-incompatible: Rename subcast param of env.dict to subcast_values for consistency with subcast_keys.
• Backwards-incompatible: Remove variable proxying. Use variable expansion instead (see 8.1.0 release notes below) (#175).
• Backwards-incompatible: Drop support for marshmallow 2 and Python 3.5, which are both EOL (#174).

8.1.0 (2020-10-31)

Features:

• Add support for variable expansion, e.g. MY_VAR=${MY_OTHER_VAR:-mydefault} (#164). Thanks gnarvaja for the PR.

Deprecations:

• Variable proxying using the {{VAR}} syntax is deprecated and will be removed in environs 9.0.0. Use variable expansion using ${VAR} instead.

# Before
export MAILGUN_LOGIN=sloria
export SMTP_LOGIN={{MAILGUN_LOGIN}}
After
export MAILGUN_LOGIN=sloria
export SMTP_LOGIN=${MAILGUN_LOGIN}

from environs import Env
env = Env(expand_vars=True)
SMTP_LOGIN = env.str("SMTP_LOGIN")  # => 'sloria'

Bug fixes:

• Fix deferred validation behavior for dj_db_url, dj_email_url, dj_cache_url, and custom parsers (#121). Thanks hukkinj1 for reporting.

Other changes:

• Test against Python 3.9.
• Remove usage of implicit typing.Optional (171).

Commits

• 5aa24db Bump version and update changelog
• a888db3 Update issue link
• 5fdb441 Rename subcast param of env.dict to subcast_values (#182)
• 80de46a Remove variable proxying (#181)
• 9c26d4a Drop Python 3.5 support (#180)
• affc0b3 Drop marshmallow 2 support (#179)
• 86813c0 Bump version and update changelog
• 2fd3e83 Test py39 in Windows; reformat azure-pipelines.yml (#178)
• d4617b2 Use explicit typing.Optional (#177)
• b9871ed Fix deferred validation with dj_* and custom parsers (#176)
• Additional commits viewable in compare view

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[dependabot]

Superseded by #26.