Try to fix update milestone

Author: david-driscoll

.github/workflows/update-milestone.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Checkout
         uses: actions/[email protected]
         with:
-          ref: ${{ github.head_ref }}
+          ref: ${{ github.sha }}
           fetch-depth: 0
 
       - name: Fetch all history for all tags and branches