Fix GitHub Actions workflow to use correct release tag reference

The workflow was failing because it used github.ref_name which is empty
for release events. Changed to use github.event.release.tag_name to
correctly extract the version number and update the major version tag.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: riglar

.github/workflows/major-release-num.yaml

@@ -1,5 +1,5 @@
 name: Update major release tag
-run-name: Update major release tag for ${{ github.ref }}
+run-name: Update major release tag for ${{ github.event.release.tag_name }}
 
 on:
   release:
@@ -22,7 +22,7 @@ jobs:
 
       - name: Update tag to major version
         run: |
-          VERSION=${{ github.ref_name }}
+          VERSION=${{ github.event.release.tag_name }}
           MAJOR=${VERSION%%.*}
 
           echo "Updating tag ${MAJOR} (source: ${VERSION}) to ${GITHUB_SHA}"