Determine the latest tag from the checked-out commit's history

The Get Latest Tag step used to pick the most recently created tag in
the entire repo, regardless of whether it is reachable from the commit
being released. In preparation for supporting releases from branches
other than master, use the nearest tag that is an ancestor of the
checked-out commit instead. This way, a patch release cut from an
older release branch bumps that branch's own latest tag even when
master already carries a newer release, and the "changes since last
release" check compares against the release that actually precedes
this one in history.

.github/workflows/release.yml

@@ -54,7 +54,7 @@ jobs:
 
       - name: Get Latest Tag
         run: |
-          latest_tag=$(git describe --tags $(git rev-list --tags --max-count=1) || echo "v0.0.0")
+          latest_tag=$(git describe --tags --abbrev=0 || echo "v0.0.0")
 
           if ! [[ $latest_tag =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
             echo "Error: Tag format is invalid. Expected format: vX.X.X"