ci: validate the PR title rather than the commit message (#1169)

If we switch the repository to require squash-and-merge strategy with
the commit using the PR title, then this makes it a lot easier to
enforce conventional commits.

Co-authored-by: Mingwei Samuel <[email protected]>

.github/workflows/conventional_commits.yml

@@ -1,13 +1,20 @@
 name: Conventional Commits
 
 on:
-  pull_request:
-    branches: [ main ]
+  pull_request_target:
+    types:
+      - opened
+      - edited
+      - synchronize
+
+permissions:
+  pull-requests: read
 
 jobs:
-  build:
+  main:
     name: Conventional Commits
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: webiny/[email protected]
+      - uses: amannn/action-semantic-pull-request@v5
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}