Remove pass by reference of the $scripts and $styles attributes in client-assets.php

[dingo-d]

Description

This removal fixes the warnings thrown while using the plugin:

Warning: Parameter 1 to gutenberg_register_vendor_scripts() expected to be a reference, value given in /wp-includes/class-wp-hook.php on line 287
Warning: Parameter 1 to gutenberg_register_packages_scripts() expected to be a reference, value given in /wp-includes/class-wp-hook.php on line 287
Warning: Parameter 1 to gutenberg_register_packages_styles() expected to be a reference, value given in /wp-includes/class-wp-hook.php on line 287

It could be related to https://core.trac.wordpress.org/ticket/44979 which was fixed in WP 5.4, so it should be removed in the plugin as well.

How has this been tested?

I've changed this in my local installation, and the warnings were gone.

Types of changes

Bug fix

Checklist:

• My code is tested (manually).
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.