For some reason the update of this file has not been applied in the
recent revisions.

Also simplify a bit the configuration of codespell moving the actual
configuration in pyproject.toml.

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being outdated).

Previous regexp does not seem to work anymore so use a simpler one.

In some marginal listing cases (Nix or Guix for now), we can receive raw file to ingest.
This commit adds a loader to ingest those. The output of the ingestion is a snapshot
with 1 branch, one HEAD branch targetting the file content ingested.

This expects to receive a mandatory 'integrity' field. It is used to check the content
match the declaration.

This can also optionally receive a list of mirror urls in case the main origin url is no
longer available. Those mirror urls are solely used as fallback to retrieve the content.

Related to T3781

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we are currently using is quite outdated and not compatible with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

To check which packages are already downloaded.

For now, this lookup is done in addition to checking the artifacts
from the last snapshot's revisions' metadata, because we did not start
writing ExtIDs yet.
But the ExtID lookup will eventually replace the artifact-based lookup.

This will finally allow us to drop the 'metadata' field of Revision
objects.

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

- blackify all the python files,
- enable black in pre-commit,
- add a black tox environment.

Related to T2134