chore: Remove 'json' module from PHP modules check

Removed 'json' module from the list of required PHP modules.

It's built-in and not possible to disable at compile time since PHP 8.0.0.

Refs:
- https://www.php.net/manual/en/json.installation.php
- https://wiki.php.net/rfc/always_enable_json
- https://www.php.net/ChangeLog-8.php#8.0.0

Signed-off-by: Josh <josh.t.richards@gmail.com>

apps/settings/lib/SetupChecks/PhpModules.php

@@ -20,7 +20,6 @@ class PhpModules implements ISetupCheck {
 		'dom',
 		'fileinfo',
 		'gd',
-		'json',
 		'mbstring',
 		'openssl',
 		'posix',