py3: fix for Python 3.12 emitting SyntaxWarning on invalid escape sequences
Mercurial became very noisy after https://github.com/python/cpython/commit/a60ddd31be7ff96a8189e7483bf1eb2071d2bddf ,
for example:
$ python3.12 mercurial/store.py
mercurial/store.py:406: SyntaxWarning: invalid escape sequence '\.'
EXCLUDED = re.compile(b'.*undo\.[^/]+\.(nd?|i)$')
This verbosity made some tests fail.
The problems were mostly insufficiently escaped regexps, relying on the Python
parser/scanner preserving invalid escape sequences.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
end_of_line = lf
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
end_of_line = lf
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false
end_of_line = lf