black: use multiline exclude definition Our excludes list is pretty complicated, so let's give ourselves some readability. Black treats multiline exclude definitions as verbse regular expressions, so we can split this up and make it easier to consume. Differential Revision: https://phab.mercurial-scm.org/D7089

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