Release candidate tags handled incorrectly

# 🐛 Summary #

When one creates a release candidate (RC) from a version such as `1.5.0-rc.1`, and then creates a prerelease for that RC, the RC Docker image has the tags `1.5.0-rc.1`, `1.5.0`, `1.5`, and `1`. This is not the desired behavior. The prerelease should only be tagged as `1.5.0-rc.1` and the other tags should only be moved once a release is created.

## To reproduce ##

Steps to reproduce the behavior:

1. Start from a descendant of this repository.
1. Create a prerelease with a tag such as `1.5.0-rc.1`.
1. Go into Docker Hub and observe that the prerelease is also tagged as `1.5.0`, `1.5`, and `1`.

## Expected behavior ##

I do not expect the creation of a prerelease to change release image tags.

Start by locating the repository's release and Docker image tagging automation, then trace how a tag such as 1.5.0-rc.1 is handled when a prerelease is created. Reproduce the Docker Hub tags described in the issue and verify that only 1.5.0-rc.1 is published for the prerelease, with version tags moving only after a release.

Written by the indexing model from the issue text.