Grid/Grid.php strtok(): Passing null to parameter #1 ($string) of type string is deprecated

[Skargne]

Hi,
In Symfony 5.4, there is a deprecation on in Grid/Grid.php line 559 :

Deprecated: strtok(): Passing null to parameter #1 ($string) of type string is deprecated

Here is a possible fix :

- $referer = strtok($this->request->headers->get('referer'), '?');
+ $referer = $this->request->headers->get('referer') ? strtok($this->request->headers->get('referer'), '?') : false;