PHP CS Fixer levels should be in lowercase and php-cs-fixer errors are not detected #94
Description
In the following lines: https://github.com/bruli/php-git-hooks/blob/master/src/PhpGitHooks/Module/PhpCsFixer/Service/PhpCsFixerTool.php#L45-L59
The php-cs-fixer levels are defined in uppercase, but php-cs-fixer fails if it uses that configuration if you run this locally:
'bin/php-cs-fixer' '--dry-run' 'fix' 'src/Cueball/PixelBundle/Controller/alpha/PixelController.php' '--level=SYMFONY'
The command fails, but the failure is not detected because on https://github.com/bruli/php-git-hooks/blob/master/src/PhpGitHooks/Module/PhpCsFixer/Infrastructure/Tool/PhpCsFixerToolProcessor.php#L79 you use the normal output and the php-cs-fixer process writes to the error output (if you change the method to use getErrorOutput you start seeing the errors)