Finish semantic-release install + configure

[mikehardy]

semantic-release correctly doing changelog generation and release type + tag, but:

• the changelog was generated but not committed before the tag+push
• github release was not created - the tag exists but it would be better to create a release + include the changelog chunk as notes automagically
• it should be run from a github workflow

Originally posted by @mikehardy in https://github.com/mikehardy/buildcache-action/issues/36#issuecomment-884541761