add a renovate configuration for terraform repo (#57)

Author: cubismod

renovate.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["github>app-sre/shared-pipelines//renovate/default.json"],
+  "gomod": {
+    "enabled": true
+  },
+  "postUpdateOptions": ["gomodTidy"]
+}