FIX remove Upload type from setUpload for Injections

[TheRealAjay]

Description

When Injecting "SilverStripe\Assets\Upload" with a custom class, the UploadReceiver.php trait throws an "Uncaught TypeError", at setUpload().

Issues

This is happening due to the "Upload" type defined in docblocks and params. Removing this type allows the Upload Class to be properly injected.

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[GuySartorelli]

Thank you for submitting this - however, the typehint is there intentionally.

Perhaps in a major release we could replace it with an interface that your custom class can implement - however you should raise an issue about that so that it can be discussed.

For now I'll close this pull request.