rust-dirstatemap: add `set_cached_mtime` helper method This will help remove the `get_or_insert` method, which is dangerous because it does not take the `DirstateMap` counters into account Differential Revision: https://phab.mercurial-scm.org/D12526

[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