Add GH workflow to reset demo

.github/workflows/reset-demo.yml

@@ -0,0 +1,51 @@
+name: Reset demo
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+  schedule:
+    - cron: '1,9,17,30,45 6,7,8 * * *'
+
+
+env:
+  PROJECT_ID: ${{ secrets.GKE_PROJECT_ID }}
+  GKE_CLUSTER: mathesar-demo
+  GKE_ZONE: us-central1
+
+
+jobs:
+  reset:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout branch
+        uses: actions/checkout@v4
+
+      - name: GCP login
+        uses: 'google-github-actions/auth@v0'
+        with:
+          credentials_json: '${{ secrets.GKE_DEMO_RESET_SA_KEY }}'
+
+      - name: Set up GKE credentials
+        uses: 'google-github-actions/get-gke-credentials@v0'
+        with:
+          cluster_name: ${{ env.GKE_CLUSTER }}
+          location: ${{ env.GKE_ZONE }}
+
+      - name: Delete existing demo deployment
+        run: kubectl delete deployments.apps demo-serve
+
+      - name: Wait until all pods are removed
+        run: >-
+          attempts=10
+          until [ $attempts -le 0 ] || [ -z "$(kubectl get pods)" ]; do
+            sleep 5
+            attempts=$((attempts - 1))
+          done
+          if [ $attempts -le 0 ]; then
+            return 1
+          fi
+
+      - name: Deploy demo
+        run: kubectl apply -f ./kubernetes_manifests/mathesar-demo.yml