Make torch_xla package PEP 561 compliant (#9515)

The repo seems to be using type hints very thoroghly, this PR adds
changes to make the package PEP 561 compliant:

https://peps.python.org/pep-0561/

This avoids errors like the following when using mypy:
```bash
infinity_emb/inference/loading_strategy.py:13: error: Cannot find implementation or library stub for module named "torch_xla"  [import-not-found]
```

Torch package does the
[same](https://github.com/pytorch/pytorch/blob/8e07c9870d07c5a318ab21bb16b3fa27576851e6/setup.py#L1288)

Author: wirthual

setup.py

@@ -466,7 +466,10 @@ def _get_jax_install_requirements():
         'importlib_metadata>=4.6;python_version<"3.10"',
     ],
     package_data={
-        'torch_xla': ['lib/*.so*',],
+        'torch_xla': [
+            'lib/*.so*',
+            'py.typed',
+        ],
     },
     entry_points={
         'console_scripts': [