PHP 8.1 deprecations

There are a collection of PHP deprecation notices when running this plugin on 8.1, including, but not limited to:

Deprecated: Return type of FS_Key_Value_Storage::offsetUnset($k) should either be compatible with ArrayAccess::offsetUnset(mixed $offset): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in .../plugins/widgets-on-pages/freemius/includes/managers/class-fs-key-value-storage.php on line 313

Looks like it’s an upstream issue in the Freemius library. The bundled version is 2.4.2, and upstream there’s a 2.5.7 available. Looking through some issues, it seems like these deprecations were resolved. Would love to see that merged in to quiet the noise.