Add job to find current branch

.github/workflows/build-and-sign-image.yml

@@ -11,6 +11,19 @@ env:
   IMAGE_NAME: ${{ github.repository }}
 
 jobs:
+  find_origin_branch:
+    runs-on: ubuntu-latest
+    outputs:
+      branch: ${{ steps.find_origin_branch.outputs.branch }}
+    steps:
+        - name: Checkout
+          uses: actions/checkout@v4
+
+        - name: Find origin branch
+          id: find_origin_branch
+          run: |
+            echo "::set-output name=branch::$(git branch -r --contains ${{ github.sha }} | grep -v HEAD | sed -e 's/^[[:space:]]*origin\///' | head -n 1)"
+
   build_and_sign_image:
     runs-on: ubuntu-latest
     permissions: