Incremental releases don't have proper versioning for Release Candidate

[doebrowsk]

Starting a new incremental release on an existing release branch is not setting the Release Candidate version correctly.

1.0.0 will correctly make 1.0.0-rc.0 on branch release-1.0. However, after v1.0.0 is released, the next Release Candidate (if one is created with a PR) would be expected to be v1.0.1-rc.0 but would instead be v1.0.0-rc.1.

The PR that creates this RC would be trigger the v1.0.1 release, so the release candidate should also be for that version. However, it can only increment the RC number.

This is a limitation of the existing action-release action we are using.