add a job to extract the branch name for the CI

.github/workflows/CI.yml

@@ -3,7 +3,17 @@ name: CI
 on: [push, workflow_dispatch] # allow manual call
 
 jobs:
-  build-and-test-linux:
+  get-branch:
+    runs-on: ubuntu-latest
+    outputs:
+      branch: ${{ steps.extract_branch.outputs.branch }}
+    steps:
+      - name: Extract branch name
+        shell: bash
+        run: echo "branch=${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}" >> $GITHUB_OUTPUT
+        id: extract_branch
+  rmg-py-ci:
+    needs: get-branch
     uses: ReactionMechanismGenerator/RMG-Py/.github/workflows/CI.yml@main
     with:
-      rmg-db-branch: ${GITHUB_REF_NAME}
+      rmg-db-branch: ${{ needs.get-branch.outputs.branch }}