PHP 8.1 - Return type issues

[jsandfordhughes]

I am using this package with PHP 8.1 and while everything works correctly there are a few warnings that popup for interface compatibility.

The ones I have seen are the following:

Return type of XeroPHP\Remote\Model::jsonSerialize() should either be compatible with JsonSerializable::jsonSerialize(): mixed

Return type of XeroPHP\Remote\Model::offsetExists($offset) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool

Return type of XeroPHP\Remote\Model::offsetGet($offset) should either be compatible with ArrayAccess::offsetGet(mixed $offset): mixed

Return type of XeroPHP\Remote\Model::offsetSet($offset, $value) should either be compatible with ArrayAccess::offsetSet(mixed $offset, mixed $value): void

Return type of XeroPHP\Remote\Model::offsetUnset($offset) should either be compatible with ArrayAccess::offsetUnset(mixed $offset): void

Happy to do a PR for these if nothing is in the pipeline?

[calcinai]

Yeah that would be great, thanks!