VIPosterior with device="mps" fails for "nsf"

[janfb]

Describe the bug
When using VIPosterior with "mps" as GPU device, and using q="nsf", and num_dim=1, then sampling from q will result in NaNs.

To Reproduce
Please add a minimal code example that reproduces the problem:

1. Python 3.11, SBI 0.22.0
2. On MacOS with MPS enabled, run pytest tests/inference_on_device_test.py::test_vi_on_gpu

Expected behavior
Sampling q should not result in NaNs.

Additional context
This issue occurs only on the MPS device and not on the CPU.
Might be related to / blocked by this PyTorch issue: pytorch/pytorch#89127

see also #912