Add packaging to github release workflow

[tomach]

Summary of the changes / Why this is an improvement

Follow-up to #521 This should fix:

Traceback (most recent call last):
  File "setup.py", line 24, in <module>
    from packaging.version import Version
ModuleNotFoundError: No module named 'packaging'

Checklist

• Link to issue this PR refers to (if applicable):
• CLA is signed