Update wgpu

[Swiiz]

Hi,

I have attempted to update the project to a recent version of wgpu (v0.25+), but I've encountered synchronization issues and test failures related to the device.poll API changes. The Maintain enum has been removed in favor of PollType, and a naive replacement seems to be insufficient.

Problem

The core issue appears to be a change in how asynchronous operations are handled in wgpu.

Steps to Reproduce

1. Update the wgpu dependency in Cargo.toml to a recent version.
2. Change device.poll(Maintain::_) to device.poll(PollType::_).
3. Run the tests.

The tests fail, and the code sometimes produce incorrect results.

Thank you for publishing this valuable project!