add initialScript to pg-safeupdate test for user creation

Author: encima

nix/ext/tests/pg_safeupdate.nix

@@ -54,6 +54,12 @@ self.inputs.nixpkgs.lib.nixos.runTest {
         enable = true;
         package = (postgresqlWithExtension psql_15);
         settings = (installedExtension "15").defaultSettings or { };
+        initialScript = pkgs.writeText "init-postgres" ''
+          CREATE ROLE authenticated NOLOGIN NOINHERIT;
+          GRANT USAGE ON SCHEMA public TO authenticated;
+          CREATE ROLE anon NOLOGIN NOINHERIT;
+          GRANT USAGE ON SCHEMA public TO anon;
+        '';
       };
 
       specialisation.postgresql17.configuration = {