* Simplify black configuration to be closer to upstream defaults

Avoid extra configuration by simply going with Black defaults. This
allows removing some configuration options, thus simplifying the overall
configuration.

It also makes the code style closer to community conventions. As more
projects adopt black formatting, more code will look like the black
defaults.

Further, the default 88 tends to create more readable lines, IMO. The
black rationale is located at:
https://black.readthedocs.io/en/stable/the_black_code_style.html#line-length

* Update tests/test_api_jws.py

Co-authored-by: José Padilla <jpadilla@webapplicate.com>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update tests/test_api_jws.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: José Padilla <jpadilla@webapplicate.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

* Fix tox "manifest" environment to pass

The command `tox -e manifest` now passes.

Added missing files to the sdist:

- .pre-commit-config.yaml
- CODE_OF_CONDUCT.md
- jwt/py.typed
- docs/

Alphabetized MANIFEST.in

Moved .flake8 to setup.cfg to avoid the need to include yet another file
to MANIFEST.in.

Exclude codecov.yml. This is for CI only.

* Move check-manifest to a pre-commit hook

Allows dropping a dependency that isn't very necessary.

The requests library was used for a single line of code. This same code
is just as easily expressible using the stdlib, thus alllows removing a
dependency.

Tests were adjusted to mock this new approach.

Now that Python 2 is not supported, can move away from type comments to
type annotation 🎉.

The typing module is always available, so remove the guards.

Specify the supported Python in the mypy configuration.

Move other mypy configurations to one place. This way, whether tox is
used or not, the same mypy errors appear.

Distribute and install PEP-561 compliant py.typed file. When PyJWT is a
imported as a library, this tells mypy to use the provided type
annotations rather than going through typeshed. This way, the types are
always up to date when running mypy.

Remove outdated ignores since dropping Python 2.

Python 3.5 went end-of-life 2020-09-30. See:
https://devguide.python.org/devcycle/#end-of-life-branches

* Run tests against Python 3.9 and add trove classifier

* Loosen pin on cryptography to allow 3.x

* Drop support for legacy contrib algorithms

* Update cryptography dep

* Introduce better experience for JWKs

* Remove explicit inheritance

* Add tests for PyJWK

* Fix failing test

* Get rid of lambda