Update LaravelLocalization.php

[MattiaMarchiorato]

check if value is not empty before str_replace because passing null to parameter #2 ($replace) of type array|string is deprecated

[niels-numbers]

Closing this one, the underlying problem is fixed by #960.

Thanks for reporting the deprecation and for the patch. We went with a different fix: substituteAttributesInRoute
now uses a single preg_replace_callback, which avoids passing null into str_replace and also handles
{param:column} bindings correctly.

One note on the patch itself, in case it is useful elsewhere: if ($value) also skips 0 and "0", so a route
parameter with the value 0 would have been left unreplaced. if ($value !== null) would be the safer form.