nextcloud-notify_push.tests: fix the eval

Without the change eval fails as:

     $ nix build --no-link -f. nextcloud-notify_push.tests
     error: attribute 'with-postgresql-and-redis27' missing
            at pkgs/servers/nextcloud/notify_push.nix:35:9:
                34|       inherit (nixosTests.nextcloud)
                35|         with-postgresql-and-redis27
                  |         ^
                36|         with-postgresql-and-redis28
            Did you mean one of with-postgresql-and-redis28 or with-postgresql-and-redis29?

pkgs/servers/nextcloud/notify_push.nix

@@ -32,7 +32,6 @@ rustPlatform.buildRustPackage rec {
     };
     tests = {
       inherit (nixosTests.nextcloud)
-        with-postgresql-and-redis27
         with-postgresql-and-redis28
         with-postgresql-and-redis29;
       inherit test_client;