ci: fetch annotated tag object in release workflow (#3)

actions/checkout at a tag-push ref materializes the tag as a
lightweight ref on the runner unless fetch-tags is set, so
  git tag -l --format='%(contents:subject)' "$tag"
returns nothing and the workflow falls back to the commit subject.
For squash-merged release PRs that subject is the auto-generated
"Release vX.Y.Z - ... (#N)" line, which is not what we want as a
release title.

Setting fetch-tags: true pulls the annotated tag object, so the
subject resolves to the message we pass via `git tag -a -m`.

Co-authored-by: Przemysław Szypowicz <2733699+pszypowicz@users.noreply.github.com>

Author: pszypowicz

.github/workflows/release.yml

@@ -19,6 +19,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd  # v5.0.1
+        # Fetch the annotated tag object itself, not just the commit it
+        # points at. Without this the tag is materialized as lightweight
+        # on the runner and `git tag -l --format='%(contents:subject)'`
+        # falls back to the commit subject - which for squash-merged PRs
+        # carries the "(#N)" suffix GitHub auto-appends.
+        with:
+          fetch-tags: true
 
       - name: Publish release
         env: