Allow finding external contributor's branch

Author: Ndpnt

.github/workflows/commit.yml

@@ -11,14 +11,10 @@ jobs:
   commitlint:
     runs-on: ubuntu-latest
     steps:
-      - name: Checkout "main" branch
-        uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-          ref: ${{ github.event.pull_request.base.ref }}
-
-      - name: Checkout the current pull request branch
-        run: git checkout ${{ github.event.pull_request.head.ref }}
+      - name: Checkout PR and "main" branches
+        run: |
+          git fetch --no-tags --depth=1 origin main +refs/pull/${{ github.event.pull_request.number }}/head:${{ github.event.pull_request.head.ref }}
+          git checkout ${{ github.event.pull_request.head.ref }}
 
       - name: Install dependencies
         run: npm ci