allow empty string as resourceTag entry (#354)

Author: vijtrip2

templates/helm/values.schema.json

@@ -192,7 +192,7 @@
       "type": "array",
       "items": {
         "type": "string",
-        "pattern": "^.*=.*$"
+        "pattern": "(^$|^.*=.*$)"
       }
     },
     "serviceAccount": {