feat: add pr labeler workflow

Signed-off-by: Adithya Krishna <adi@documenso.com>

.github/workflows/pr-labeler.yml

@@ -0,0 +1,20 @@
+name: "PR Labeler"
+
+on:
+  - pull_request_target
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  labeler:
+    permissions:
+      contents: read
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/labeler@v4
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          sync-labels: ""