Drop Haiku CI/CD testing on GPU.

It seems like GPU support is broken again due to conflicting version
installation. This does not mean that our code is broken, but for
now we will drop testing it as part of the CI/CD.

tox.ini

@@ -28,10 +28,6 @@ extras =
     all,tests
 allowlist_externals =
     bash
-commands_pre =
-    # Install JaxLib compiled with CUDA 12 support.
-    pip install jax[cuda12_pip]~=0.4.1 \
-      -f https://storage.googleapis.com/jax-releases/jax_cuda_releases.html
 commands =
     bash scripts/run_tests.sh lint_code
     bash scripts/run_tests.sh lint_tests