add validate workflow

.github/workflows/validate.yaml

@@ -0,0 +1,18 @@
+name: Validate terraform module
+
+on:
+  pull_request:
+    branches:
+      - '*'
+
+jobs: 
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: module terraform init
+        run: terraform init
+      - name: module terraform fmt
+        run: terraform fmt
+      - name: validate configuration
+        run: terraform validate