Merge pull request #29 from creative-commoners/pulls/2/php84

API Explicity mark nullable parameters for PHP 8.4

src/FacebookWebDriver.php

@@ -1105,7 +1105,7 @@ public function getWebDriverSessionId()
      * @param RemoteWebElement|null $parent Optional parent element
      * @return RemoteWebElement
      */
-    private function findElement($xpath, RemoteWebElement $parent = null)
+    private function findElement($xpath, ?RemoteWebElement $parent = null)
     {
         $finder = WebDriverBy::xpath($xpath);
         return $parent