Build aarch64 wheels natively

[tongyuantongyu]

Cross compiling mis-compiled something inside the Rust TLS stack causing downloading the vocab file to consistently fail on ARM64 platform (#71):

>>> from openai_harmony import load_harmony_encoding
>>> load_harmony_encoding("HarmonyGptOss")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "lib/python3.12/site-packages/openai_harmony/__init__.py", line 699, in load_harmony_encoding
    inner: _PyHarmonyEncoding = _load_harmony_encoding(name)
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
openai_harmony.HarmonyError: error downloading or loading vocab file: failed to download or load vocab file

Natively built wheels work fine, and GitHub has ARM64 runners, so simply build them natively.