CI: Add GitHub workflow to schedule a PR with changes to Alerting Swagger spec (#71794)

* add github workflow to schedule alerting swagger spec pr

* also generate stable api spec

.github/CODEOWNERS

@@ -594,6 +594,7 @@ embed.go @grafana/grafana-as-code
 /.github/pr-commands.json @marefr
 /.github/renovate.json5 @grafana/frontend-ops
 /.github/teams.yml @armandgrillet
+/.github/workflows/alerting-swagger-gen.yml @grafana/alerting-backend-product
 /.github/workflows/auto-milestone.yml @grafana/grafana-delivery
 /.github/workflows/backport.yml @grafana/grafana-delivery
 /.github/workflows/bump-version.yml @grafana/grafana-delivery

.github/workflows/alerting-swagger-gen.yml

@@ -0,0 +1,37 @@
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 0 * * 1'
+
+jobs:
+  gen-swagger:
+    name: Alerting Swagger spec generation cron job
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 2
+      - name: Set go version
+        uses: actions/setup-go@v4
+        with:
+          go-version: '1.20.6'
+      - name: Build swagger
+        run: |
+          make -C pkg/services/ngalert/api/tooling post.json api.json
+      - name: Open Pull Request
+        uses: peter-evans/create-pull-request@v3
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          commit-message: "chore: update alerting swagger spec"
+          title: "Alerting: Update Swagger spec"
+          body: |
+            This is an automated pull request to update the alerting swagger spec.
+            Please review and merge.
+          branch: update-alerting-swagger-spec
+          delete-branch: true
+          labels: 'area/alerting,type/docs,no-backport,no-changelog'
+          team-reviewers: 'grafana/alerting-backend-product'
+          draft: false
+