Get v3 into stable

[GCHQ-Developer-530]

Summary

We need to find out:

• What stable means
• What stable needs
• Whether there's any final breaking changes to make otherwise it needs moving to v4

💬 Description

Should just be final checks over the package to make sure there's nothing left that needs to be done to ensure that v3 is going to be stable and not just an alpha pre-release.

[evenstensberg]

Any chance to get #2617 merged in v3 if approved? If not, it has to wait for v4