feat: make tick function usable without leaf

Author: mychidarko

src/functions.php

@@ -2,14 +2,18 @@
 
 declare(strict_types=1);
 
-if (!function_exists('tick') && class_exists('Leaf\App')) {
+if (!function_exists('tick')) {
     /**
      * Return the leaf date instance
      *
      * @return Leaf\Date
      */
     function tick(string $userDate = null, string $userTimeZone = null)
     {
+        if (!class_exists('Leaf\App')) {
+            return (new Leaf\Date())->tick($userDate, $userTimeZone);
+        }
+
         $date = Leaf\Config::get('date')['instance'] ?? null;
 
         if (!$date) {