ci: Add dist job
Quoting the last commit:
So far, releases are done locally by invoking `meson dist`.
We can do better and leverage the existing CI infrastructure, to get
to the following release workflow:
- bump version in meson.build, update NEWS etc.
- open merge request for the release
- merge when the pipeline (including dist check) succeeds
- tag the release
- wait for the tag pipeline to spit out the tarball artifact