test: correct test_admin_ready_includes_schema_cache_state

There was an oversight on d556cea, `timeout_authenticator` doesn't have
any privileges on the tables so it shouldn't be making requests to the
API server or it will end up with 401 responses.

test/io/test_io.py

@@ -605,7 +605,7 @@ def test_admin_ready_includes_schema_cache_state(defaultenv, metapostgrest):
     env = {
         **defaultenv,
         "PGUSER": role,
-        "PGRST_DB_ANON_ROLE": role,
+        "PGRST_DB_ANON_ROLE": "postgrest_test_anonymous",
         "PGRST_INTERNAL_SCHEMA_CACHE_QUERY_SLEEP": "500",
     }