Replace global $a with BaseObject::getApp()

src/Worker/ForkHook.php

@@ -7,9 +7,11 @@ namespace Friendica\Worker;
 
 use Friendica\Core\Addon;
 
-Class ForkHook {
-	public static function execute($name, $hook, $data) {
-		global $a;
+Class ForkHook
+{
+	public static function execute($name, $hook, $data)
+	{
+		$a = \Friendica\BaseObject::getApp();
 
 		Addon::callSingleHook($a, $name, $hook, $data);
 	}