feat(ci): Add workflow to automate release branch creation (#1092)

Prevent workflow execution from non-default branches.

Author: anaiberta

.github/workflows/create-release-branch.yml

@@ -26,6 +26,16 @@ jobs:
     name: Validate permissions
     runs-on: ubuntu-latest
     steps:
+      - name: Check default branch
+        env:
+          REF: ${{ github.ref_name }}
+          DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
+        run: |
+          if [ "$REF" != "$DEFAULT_BRANCH" ]; then
+            echo "::error::This workflow can only be run from the default branch (${DEFAULT_BRANCH}), but was triggered from '${REF}'."
+            exit 1
+          fi
+
       - name: Check admin permission
         env:
           GH_TOKEN: ${{ github.token }}