The Release workflow fails when there are no changelog entries in the release

Happens during the "Update Redmine" step during publish, so most of the release has already happened (packages are updated on pypi and rubygems, etc.).

The error encountered is:

python3 .ci/scripts/redmine.py $REDMINE_QUERY_URL $MILESTONE_URL $RELEASE
Traceback (most recent call last):
  File ".ci/scripts/redmine.py", line 27, in <module>
    status = redmine.issue.get(int(issue)).status.name
ValueError: invalid literal for int() with base 10: ''

See here for the full workflow: https://github.com/pulp/pulp_deb/runs/4223060338?check_suite_focus=true

Expectation:

If there are no issues in the release, then .ci/scripts/redmine.py does not need to do anything, and should just return 0!

Release steps not performed because they come after the error:

• Create release on GitHub
• Cleanup repository before making changelog PR
• Stage changelog for master branch
• Create Pull Request for Changelog

=> The changelog steps might also need some special handling to deal with this special case of "no changelog entries".

Start with .ci/scripts/redmine.py and the release workflow's "Update Redmine" step. Reproduce a release with no changelog entries and inspect how the later changelog steps handle the empty case. Done means the workflow completes the remaining release steps without the empty issue value causing an error.