Release 4.0.0 - Githubissues

This issue serves as a checklist for the release event.

[x] Secure the CI is green on git main
[x] Check that dependencies ranges are ok, upgrade if needed
[x] Adjust version in __about__.py to x.x.x
[x] Update Github milestone to match the issues that will be released
[x] Close Github milestone
[x] Update the Changelog so that it is in line with the content of Github milestone
[x] Push a tag on Github named vx.x.x
[x] Create a Github release, pointing to the tag, with the Changelog of this release
[x] Publish the Github release (this will trigger the CI, if the CI fails and you have to push a minor fix which does not justify to create a new version, you will have to delete the release and re-create it from scratch)
[x] Check that version is published as a Github release at https://github.com/openzim/python-scraperlib/releases and tagged Latest
[x] Check that version is published on Pypi at https://pypi.org/project/zimscraperlib/
[x] Create a new Github milestone with the next version incrementaly (a priori a minor one)
[x] Create a new Github issue attached to this milestone with this checklist inside
[x] Create new ## [Unreleased] section in Changelog (placeholder for future entries)
[x] Adjust version in __about__.py to x.y.z+1-dev0(next patch a priori )
[x] Inform #scrapers channel on Slack about the new version

openzim / python-scraperlib