CI: add dry run job

.github/workflows/dry-run.yml

@@ -0,0 +1,25 @@
+name: Dry Run
+on:
+  push:
+  workflow_dispatch:
+  schedule:
+    # Try to dry run every 4 hours
+    - cron: "0 */4 * * *"
+
+jobs:
+  dry-run:
+    name: Run sync-team dry-run
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Generate GitHub token
+        uses: actions/create-github-app-token@v1
+        id: generate-token
+        with:
+          # GitHub App ID secret name
+          app-id: ${{ secrets.GH_APP_ID }}
+          # GitHub App private key secret name
+          private-key: ${{ secrets.GH_APP_PRIVATE_KEY }}
+      - name: Dry run
+        env:
+          GITHUB_TOKEN: ${{ steps.generate-token.outputs.token }}
+        run: cargo run -- --only-print-plan github