Publish the annotated tag message as the release body

akkuman/gitea-release-action takes body/body_path but does not fall
back to the tag annotation, so v1.2.0 published with empty notes.
Write the tag body to a file and pass it; fetch-depth 0 so the
annotated tag object is present to read it from.

.gitea/workflows/build-pcm.yml

@@ -13,6 +13,8 @@ jobs:
       # third-party actions pinned to commit SHAs: mutable tags could be
       # repointed at malicious code that runs with repo/token access
       - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+        with:
+          fetch-depth: 0        # the annotated tag carries the release notes
 
       - name: Check tag matches metadata.json version
         if: startsWith(github.ref, 'refs/tags/v')
@@ -35,10 +37,20 @@ jobs:
             dist/*.zip
             dist/metadata-registry.json
 
+      # the action does not fall back to the tag annotation, so an
+      # un-bodied release publishes with empty notes (as v1.2.0 did)
+      - name: Release notes from the annotated tag
+        if: startsWith(github.ref, 'refs/tags/v')
+        run: |
+          git tag -l --format='%(contents:body)' "$GITHUB_REF_NAME" \
+            > release-notes.md
+          cat release-notes.md
+
       - name: Create release with the zip, registry metadata and figures
         if: startsWith(github.ref, 'refs/tags/v')
         uses: akkuman/gitea-release-action@b8d9144f302c68610911db1aaf722708d5c02d94 # v1
         with:
+          body_path: release-notes.md
           files: |
             dist/*.zip
             dist/metadata-registry.json