Run tests on Linux and Windows on CI

[jonmmease]

#39 added support for running tests on GitHub actions with the macos runner, as this was easy to get up and running. Both windows and linux require extra configuration to support wgpu in GitHub Actions.

Here is the config that the wgpu project itself uses: https://github.com/gfx-rs/wgpu/blob/trunk/.github/workflows/ci.yml

Hopefully we can follow this to get Linux and Windows tests working.