Mark param explicitly as nullable

- Deprecated: ipl\Stdlib\Str::trimSplit(): Implicitly marking parameter $limit as nullable is deprecated, the explicit nullable type must be used instead

Author: sukhwinder33445

src/Str.php

@@ -76,7 +76,7 @@ public static function symmetricSplit(?string $subject, string $delimiter, int $
      *
      * @return array<string>
      */
-    public static function trimSplit(?string $subject, string $delimiter = ',', int $limit = null)
+    public static function trimSplit(?string $subject, string $delimiter = ',', ?int $limit = null)
     {
         if ($subject === null || empty($delimiter)) {
             return [];