format-source 4.0

[Pierre-Yves David]

For your information we tagged and published version 4.0 of format 
source extensions.

The following items have been improved.

*    ship with default configuration for the following tools:
   - clang-format,
   - black,
   - yapf,
   - gofmt,
   - rustfmt,
   - prettier,
* improved file pattern support,
* improved error handling,
* improved configuration for tools inputs/outputs method,
* dropped compatibility with Mercurial < 4.4,
* format-source's sources are now formatted with black.

Cheers

-- 
Pierre-Yves David