chore: add notification action

[skip ci]

.github/workflows/notify_pr.yaml

@@ -0,0 +1,22 @@
+name: Notify Google Chat on new PR
+
+on:
+  pull_request:
+    types:
+      - opened
+
+jobs:
+  notify-pr-google-chat:
+    runs-on: docker
+    container:
+      image: alpine:latest
+    steps:
+      - name: Notify
+        uses: ./.github/actions/notify
+        with:
+          title: New Pull Request
+          event_title: ${{ github.event.pull_request.title }}
+          event_author: ${{ github.event.pull_request.user.login }}
+          event_body: ${{ github.event.pull_request.body || 'No description provided.' }}
+          event_number: ${{ github.event.pull_request.number }}
+          event_url: ${{ github.event.pull_request.html_url }}