Permit callable arguments to be understood

[cs278]

I forgot to add this into #4.

Upgrading to 1.1 seeing PHPStan errors when decorating a callable which has arguments:

Parameter #1 $operation of method Tobion\Retry\RetryConfigurator::decorate() expects callable(): void, Closure(bool): void given.

This fixes them.

[sn109946]

src/RetryConfigurator.php