typing: add missing signature for mercurial.cext.parsers.parse_index2()
Flagged by pytype 2022.11.18 when the cext stubs are made visible to it. There
are very likely other signatures that are missing, but this is enough to keep it
happy for now.
[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