This commit changes our release process from the model of having a
release commit (and pull request) which also updated the NEWS.md file
and bumped the versions in the osbuild.spec and setup.py files to simply
pushing a tag.
After the tag (containing the release notes) is pushed, a GitHub
composite action is triggered that creates a GitHub release with the
contents of the git release tag. Furthermore the bumping of the version
number now always has to happen directly after a release to avoid having
to push a(n untested) commit to main for the release and this is also
handled by the GitHub composite action.
Finally packit pushes directly to dist-git now on pushing the release
tag, so no pull-request needs to be reviewed and merged anymore.
Consequently, we also drop the docs/news folder and its content and
adjust the PR template.
The template mentioned only "adequate" documentation which can be
interpreted in many ways. Mention the news/unreleased directory and the
guides explicitly and include links for convenience.
The majority of pull requests do not fix a downstream issue. In
practice, people usually delete the whole suggested content.
Move it into a comment, so that this step is unnecessary.
