If you accidentally tag the wrong commit, or if you have a new commit before publishing then you may be able to re-tag without incrementing your library's version #
git push origin :refs/tags/0.21.0
git tag -d 0.21.0
git tag 0.21.0 e242d7263481a2a375f3f2b38c3cf849ddbce457
git push origin 0.21.0
When I deleted the remote tag, the release lost its reference to the tag, so it reverted from a Release to a Draft Release.
Navigate to Release and re-release on Github
Context: I had tagged a commit but there was an error in the Gradle Publish task. I had to push a commit to fix this but had already "released" a tag on Github. I didn't want to increment the version so these were the steps I took.