[BUG] ExportLensActionRequest::availableLenses is not a valid override of LensActionRequest::availableLenses

[TjarcoKerssens]

When adding download functionality to a Lens, the request will fail because on line 55 in ExportLensActionRequest, the method availableLenses is not a valid override of Laravel\Nova\Http\Requests\LensActionRequest::availableLenses().

How to fix, change the method to:

public function availableLenses(): Collection

[Claw666]

@patrickbrouwers have you had a chance to look at this by any chance? There is a PR already for the fix too!