gymnasium: disable doCheck on Darwin

if doCheck = true on darwin, jaxlib is evaluated, which errors

pkgs/development/python-modules/gymnasium/default.nix

@@ -20,6 +20,7 @@
 , pygame
 , pytestCheckHook
 , scipy
+, stdenv
 }:
 
 buildPythonPackage rec {
@@ -60,6 +61,12 @@ buildPythonPackage rec {
     scipy
   ];
 
+  # if `doCheck = true` on Darwin, `jaxlib` is evaluated, which is both
+  # marked as broken and throws an error during evaluation if the package is evaluated anyway.
+  # disabling checks on Darwin avoids this and allows the package to be built.
+  # if jaxlib is ever fixed on Darwin, remove this.
+  doCheck = !stdenv.isDarwin;
+
   disabledTestPaths = [
     # mujoco is required for those tests but the mujoco python bindings are not packaged in nixpkgs.
     "tests/envs/mujoco/test_mujoco_custom_env.py"