* remove reference in comments to python3.6

* upgrade tox python env in script

* bump python version in example for completeness

* upgrade python version requirement in setup doc

* upgrade necessary python version in __init__.py

* upgrade python version in setup.py

* newsfragment

* drops refs to bionic and replace with focal

* bump refs to postgres 9.6 to 10

* fix hanging ci

* try installing tzdata first

* revert change made in b979f336

* ignore new random mypy error while debugging other error

* fix lint error for temporary workaround

* revert change to install list

* try passing env var

* export debian frontend var?

* move line and add comment

* bump pillow dependency

* bump lxml depenency

* install libjpeg-dev for pillow

* bump automat version to one compatible with py3.8

* add libwebp for pillow

* bump twisted trunk python version

* change suffix of newsfragment

* remove redundant python 3.7 checks

* lint

* remove python 3.6 and postgres 9.6 from github workflow

* remove python 3.6 env from tox

* newsfragment

* correct postgres version

* add py310 to tox env list

Signed-off-by: Nick Barrett <nick@beeper.com>

Turns out these scripts weren't getting linted.

I went through and removed a bunch of cruft that was lying around for compatibility with old Python versions. This PR also will now prevent Synapse from starting unless you're running Python 3.6+.

Apparently on tox 2.5, `usedevelop` overrides `skip_install`, so we end up
trying to install the full dependencies even for the `-old` environment.

This also pins the Twisted version in the mypy job for CI until
proper type hints are fixed throughout Synapse.

Co-authored-by: Dan Callahan <danc@element.io>

pip 21.0 stopped supporting Python 3.5.

Co-authored-by: Dan Callahan <danc@element.io>

pip 21.0 stopped supporting Python 3.5.

As we use `execute_values` with the `fetch` parameter.

The lists of source directories to lint between `tox.ini` and `lint.sh` became out of sync. This PR tightens them up and adds some comments reminding any future readers to keep the list in sync.

setuptools 51.0.0 dropped support for Python 3.5.

We were running some linters on some files and some on others. Extract a common
setting and use it everywhere.

... for running the tests with no optional deps.

... and disable coverage tracking for mypy and friends.

The test runner isn't present in the `[all]` set of extras, so the
previous instructions did not work without also installing `[test]`.

Note that this does not include the `[lint]` extras, since those do not
install on all supported Python versions (specifically, isort 5.x
requires Python 3.6, while we still support 3.5). Instructions for that
are included in our pull request template, so we should be fine there.

I've also dropped the `--no-use-pep517` arg to `pip install` since it
seems to have been added to address a temporary regression in pip 19.1
which was fixed in pip 19.1.1 the following month.

Lastly, updated the example output of the test suite to set more
realistic expectations around run time.

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

As expected, all tests pass locally without modification.

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

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

Lint dependencies can now be installed with pip install -e ".[lint]"

This should help keep the version in sync between tox and documentation.

Duplicating function signatures between server.py and server.pyi is
silly. This commit changes that by changing all `build_*` methods to
`get_*` methods and changing the `_make_dependency_method` to work work
as a descriptor that caches the produced value.

There are some changes in other files that were made to fix the typing
in server.py.

Run `isort`, `flake8` and `black` over the `contrib/` directory and `synctl` script. The latter was already being done in CI, but now the linting script does it too.

Fixes https://github.com/matrix-org/synapse/issues/7910

The CI appears to use the latest version of isort, which is a problem when isort gets a major version bump. Rather than try to pin the version, I've done the necessary to make isort5 happy with synapse.

fix a few things to make this pass mypy.