Add PHP 8.4 support.

Author: ivopetkov

composer.json

@@ -16,7 +16,7 @@
         }
     ],
     "require": {
-        "php": "7.1.*|7.2.*|7.3.*|7.4.*|8.0.*|8.1.*|8.2.*|8.3.*"
+        "php": "7.1.*|7.2.*|7.3.*|7.4.*|8.0.*|8.1.*|8.2.*|8.3.*|8.4.*"
     },
     "require-dev": {
         "ivopetkov/docs-generator": "1.*"

src/DataListTrait.php

@@ -324,11 +324,11 @@ public function concat($list): self
      * Extract a slice of the list.
      * 
      * @param int $offset The index position where the extraction should begin
-     * @param int $length The max length of the items in the extracted slice.
+     * @param int|null $length The max length of the items in the extracted slice.
      * @return mixed Returns a slice of the list.
      * @throws \InvalidArgumentException
      */
-    public function slice(int $offset, int $length = null)
+    public function slice(int $offset, ?int $length = null)
     {
         $actions = $this->internalDataListActions;
         $actions[] = ['slice', $offset, $length];