Release wheels on tags

[LDiazN]

This PR will change the current github workflow for creating wheels to publish them only when a new version tag is created.

Also adds an utility script to create the tag properly formatted.

The script will:

• Check that the local version of ooniauth-py is greater than the one in pypi
• Check that the current branch is main, to prevent releasing from the wrong branch
• Check that the new tag does not exists already
• Set up an auto incrementing number for the tags
• Format the tag name properly
• Push the tag

Example output:

Checking last version from PyPi...
Version number OK!
Release tag preview:
  Tag scheme:     userauth-<shortsha>-<release_number>
  Release number: 2
  Tag:            userauth-d1727c3-2
  Branch:         release-on-tags (WARNING: not main)
  Commit:         d1727c3
  ooniauth-py:    0.2.1 (PyPI: 0.2.0)

  WARNING: current branch is 'release-on-tags' (not main): commit d1727c3 is not in main
Create and push tag  userauth-d1727c3-2  to origin? [y/N] y
Done: pushed userauth-d1727c3-2