rust: fix build errors on darwin I'm not all _that_ versed in Rust, but I think the root cause is that some constants are u16 rather than u32 on Darwin. I checked that the code still compiles on the latest Ubuntu. Differential Revision: https://phab.mercurial-scm.org/D11955

[build-system]
requires = ["setuptools", "wheel"]

[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true