Support for TimesFM-2.0 models

1. Add support for v2.0
2. Some bug fixes in pytorch decoding.
3. Right now we do not support cached decoding in both jax and pytorch

TimesFM v1.2.1

Changes:

• PyTorch support for TimesFM inference.

PyPI Release:

v1.2.1: Support separate dependencies for pax and torch versions of TimesFM:

• pip install timesfm[pax] for the pax version and jax checkpoints.
• pip install timesfm[torch] for the torch version and checkpoints.
• See the updated README for the usage.

Checkpoints:

The PyTorch checkpoint for the 200m model is available on Hugging Face:

• https://huggingface.co/google/timesfm-1.0-200m-pytorch

Full Changelog:

https://github.com/google-research/timesfm/commits/v1.2.1