This fixes python 3.7 support due to poetry, a dependency of isort, that
removed support for that Python version in a recent release.

- pre-commit from 4.1.0 to 4.3.0,
- codespell from 2.2.1 to 2.2.2,
- black from 22.3.0 to 22.10.0 and
- flake8 from 4.0.1 to 5.0.4. Also freeze flake8 dependencies.

Also change flake8's repo config to github (the gitlab mirror
being outdated).

That hook can be frustrating as it can discard a long commit message
if it finds a typo in it so better removing it.

black is considered stable since release 22.1.0 and the version
we are currently using is quite outdated and not compatible with
click 8.1.0, so it is time to bump it to its latest stable release.

Please note that E501 pycodestyle warning related to line length
is replaced by B950 one from flake8-bugbear as recommended by black.
https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#line-length

Related to T3922

To install the new hook:

  $ pre-commit install -t commit-msg

Related to T2610

flake8 hook has been removed from https://github.com/pre-commit/pre-commit-hooks
so now use the one from https://gitlab.com/pycqa/flake8

This requires some more stub-missing entries declared in mypy.ini to pass OK.

and document it briefly in the README file.

This comes with a few checkers:
- flake8
- trailing-whitespace
- check-json
- check-yaml
- codespell

Also include commented checkers:
- black: disabled since we are not ready for this yet,
- pydocstyle: disabled since we have way too many pydoctyle errors for now...

See https://pre-commit.com/ for more details.

Related to T1881.