notify: cast hash to bytes
This is needed to avoid a str/bytes mismatch when interpolating a
line or 2 later.
Differential Revision: https://phab.mercurial-scm.org/D7021
[tool.black]
line-length = 80
exclude = 'build/|wheelhouse/|dist/|packages/|\.hg/|\.mypy_cache/|\.venv/|mercurial/thirdparty/|hgext/fsmonitor/pywatchman/|contrib/python-zstandard/'