ci: enforce rebase

.github/workflows/test_and_deploy.yml

@@ -1,8 +1,43 @@
 name: Build, Test, and Deploy
 
-on: [pull_request]
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+  push:
+    branches:
+      - master
+
 jobs:
+  check-rebase:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Fetch all branches
+        run: |
+          git fetch --all
+
+      - name: Check for divergence from master
+        run: |
+          git fetch origin master
+          UPSTREAM=${{ github.base_ref }} # Target branch of the pull request (usually master)
+          CURRENT=$(git rev-parse HEAD)  # Latest commit on the PR branch
+          MERGED=$(git merge-base HEAD origin/$UPSTREAM) # Common ancestor between HEAD and master
+          
+          if [ "$MERGED" != "$CURRENT" ]; then
+            echo "This branch is not rebased with the latest master."
+            exit 1
+          else
+            echo "This branch is up-to-date with master."
+          fi
+
   build:
+    needs: check-rebase
     runs-on: ubuntu-latest
 
     steps: