Traditionally pytest publishes tags in the form `X.Y.Z`, however the deploy workflow (copied from somewhere else) published tags in the form `vX.Y.Z`.
This is the root cause of #11548, because it tried to publish the release notes for tag `X.Y.Z` (which did not exist).
Fix#11548
As discussed in #11408:
* Improve documentation for the release process.
* Fix the description for the PRs created by the `prepare release pr` workflow.
* Fix pushing tag in the `deploy` workflow.
* Build the package only once, and test on all platforms.
* Deploy is now triggered manually via an Action, which is then responsible for tagging the repository after the package has been uploaded successfully.
* Drop 'docs': we nowadays rely on readthedocs preview PR builds.
Otherwise we see this warning:
Warning: You are using "pypa/gh-action-pypi-publish@master". The "master" branch of this project has been sunset and will not receive any updates, not even security bug fixes. Please, make sure to use a supported version. If you want to pin to v1 major version, use "pypa/gh-action-pypi-publish@release/v1". If you feel adventurous, you may opt to use use "pypa/gh-action-pypi-publish@unstable/v1" instead. A more general recommendation is to pin to exact tags or commit shas.
This will trigger a deploy directly when a tag is pushed, avoiding
having to wait for another lenghty build.
This is safe since we only push release tags after the release PR has passed all its tests.
See comments in #9793.