Narrower return types for restore_error_handler() and restore_exception_handler()

[johnbillion]

Both of these functions always return true. Narrowing their documented return types prevents confusion around whether the return value can be used to determine success or failure, which it cannot.

• https://3v4l.org/MO18a
• https://phpstan.org/r/3135c610-85c9-4891-840e-79cdda94b7fb
• https://www.php.net/manual/en/function.restore-error-handler.php
• https://www.php.net/manual/en/function.restore-exception-handler.php

[ondrejmirtes]

Thank you!