Merge pull request ethereum#325 from OffchainLabs/design-approved-check

Block merging if `design-approved` label missing

.github/workflows/merge-checks.yml

@@ -0,0 +1,20 @@
+name: Merge Checks
+
+on:
+  pull_request:
+    branches: [ master ]
+    types: [synchronize, opened, reopened, labeled, unlabeled]
+
+jobs:
+  design-approved-check:
+    if: ${{ !contains(github.event.*.labels.*.name, 'design-approved') }}
+    name: Design Approved Check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check for design-approved label
+        run: |
+          echo "Pull request is missing the 'design-approved' label"
+          echo "This workflow fails so that the pull request cannot be merged"
+          exit 1
+
+