Some error messages to skip

Author: Mytherin

test/configs/attach_postgres.json

@@ -9,7 +9,8 @@
     "postgres_scanner"
   ],
   "skip_error_messages": [
-    "zkxjvhckjhsdfkjhfdsakjh"
+    "RETURNING is not implemented for Postgres yet",
+    "SET DEFAULT is not yet supported for updates of a Postgres table"
   ],
   "skip_tests": [
     {