Publish a release candidate to check improvements have been successful

[NickColley]

What

Publish 6.2.0-rc.0 to check the improvements to the release process have succeeded

Why

We've changed a few things so be good to make sure it's working as expected before a stable release

Who needs to work on this

Developers

Done when

• Try creating a branch called support/blah and ensure it gets rejected
• Try running the workflow on a non-protected branch e.g. blah with the production environment set and confirm it rejects
• Try running process for real with the rc
• Check provenance still works as expected
• Check the documentation matches the process