Use PHP-CS-Fixer 3.14.x instead of 3.13.1

[Frederik Sauer]

This version has much expected fixes to binary_operator_spaces and improved handling of PHPDoc for \Closure
https://github.com/PHP-CS-Fixer/PHP-CS-Fixer/releases/tag/v3.14.0

[Dries Vints]

Thanks, I've sent in a PR to bump it: #143