Make `useAsset`'s `onProgress` type optional

[trezy]

Description of change

Does what it says on the tin.

Fixes: #502

Pre-Merge Checklist

• [x] Tests and/or benchmarks are included
• [x] Documentation is changed or added
• [x] Lint process passed (npm run lint)

[github-actions[bot]]

:tada: This issue has been resolved in version 8.0.0-beta.2 :tada:

The release is available on GitHub release

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