pyproject: add config file
This will tell pip et al to call our setup.py for the majority of
packaging concerns, but also gives us a place to put standard config
stuff like black.
Differential Revision: https://phab.mercurial-scm.org/D9833
BasedOnStyle: LLVM
IndentWidth: 8
UseTab: ForIndentation
BreakBeforeBraces: Linux
AllowShortIfStatementsOnASingleLine: false
IndentCaseLabels: false
AllowShortBlocksOnASingleLine: false
AllowShortFunctionsOnASingleLine: false
IncludeCategories:
- Regex: '^<'
Priority: 1
- Regex: '^"'
Priority: 2