Bad deprecation when using $type=null with Redis::scan

Redis::scan is defined as:
```php
public function scan(?int &$iterator, ?string $pattern = null, int $count = 0, string $type = NULL): array|false;
```

Yet, if we call the method with $type = null, we get a deprecation:
`Redis::scan(): Passing null to parameter #4 ($type) of type string is deprecated`

I suppose the argument is missing a nullable flag in its arginfo definition.