ci: add reminder to deploy TF cloud changes

.github/workflows/deployminder.yml

@@ -0,0 +1,37 @@
+name: Deploy Reminder
+
+on:
+  pull_request:
+    types:
+      - closed
+    branches:
+      - main
+
+jobs:
+  remind:
+    if: github.event.pull_request.merged == true
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check for changes in infra/
+        id: check_changes
+        run: |
+          git diff --name-only ${{ github.event.pull_request.base.sha }} ${{ github.event.pull_request.head.sha }} | grep -q '^infra/'
+          echo "has_infra_changes=$?" >> $GITHUB_OUTPUT
+
+      - name: Comment on PR
+        if: steps.check_changes.outputs.has_infra_changes == '0'
+        uses: actions/github-script@v7
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: 'Changes detected in the `infra/` directory. Don\'t forget to apply these changes in Terraform Cloud and/or Fastly!'
+            })