Updating mypy past version 0.9 means that third-party stubs are no-longer distributed with typeshed. See http://mypy-lang.blogspot.com/2021/06/mypy-0900-released.html

 for details.
We therefore pull in stub packages in setup.py

Additionally, some modules that we were previously ignoring import failures for now have stubs. So let's use them.

The rest of this change consists of fixups to make the newer mypy + stubs pass CI.

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

Reformat all files with the new version.

Signed-off-by: Marcus Hoffmann <bubu@bubu1.eu>

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

* Drop Python 3.5 from Trove classifier metadata.

Signed-off-by: Dan Callahan <danc@element.io>

This fixes an error ("Cannot determine consistent method resolution order (MRO)")
when running mypy with a cache.

* Adds B00 to ignored checks.
* Fixes remaining issues.

 - Update black version to the latest
 - Run black auto formatting over the codebase
    - Run autoformatting according to [`docs/code_style.md
`](https://github.com/matrix-org/synapse/blob/80d6dc9783aa80886a133756028984dbf8920168/docs/code_style.md)
 - Update `code_style.md` docs around installing black to use the correct version

This new version no longer has the problem of adding/removing a blank line in `.pyi` files, which black disagrees with. This would cause `isort` to slightly modify `.pyi` files, before `black` would subsequently modify back directly afterwards.

Relevant `isort` issue: https://github.com/pycqa/isort/issues/1284

This avoids a warning when uploading packages to PyPI via twine.

As expected, all tests pass locally without modification.

Signed-off-by: Dan Callahan <danc@element.io>

This PR makes several changes to the `./scripts-dev/lint.sh` script, which lints the codebase with a number of tools:

* Adds usage information, with `-h` flag to show it. Otherwise it will show when providing an unknown flag.
* Adds option `-d` which will check both staged and unstaged files that have changed since the last commit and add them to the list of files to lint.
  - Note that only files without an extension, or with a `.py` extension will be allowed. This prevents editing bash scripts causing the linters to break on non-python files.
* Improves the print-out of which files/directories are being linted. 

moves non-runtime dependencies out of synapse.python_dependencies (test and lint)

Synapse supports Python 3.8. We've been using it in CI for a while now.

* remove 2.7 from CI and publishing

* fill out classifiers and also make it not be installed on 3.5

* some minor bumps so that the old deps work on python 3.5

Using systemd-python allows for logging to the systemd journal,
as is documented in: `synapse/contrib/systemd/log_config.yaml`.

Signed-off-by: Silke Hofstra <silke@slxh.eu>

Make the dependencies more like a standard Python project and hook up the optional dependencies to setuptools (#4298)

Using tox to run the tests is a bad idea, as per the comments.

Seperate scripts/ into scripts/ and scripts-dev/, where scripts/* are automatically added to the package