+local version needs to be retained into deploy stage

Job #13548 failed for bb0bfec9:

The version in pyproject.toml that the build stage sets is lost in the dpeloy stage. We need to either set the version in deploy as well, or cache pyproject.toml to retain it.

Once #317 (moved) is done, it seems we can just set the version in a global before_script here because all jobs that do not work with the tree directly are then moved to the distribution project.