Wgpu

Added:

* Official support for Windows 3.10.
* The `max_fps` argument can be provided to a canvas.
* The glfw gui backend supports user events in the same manner as the jupyter gui backend,
using the [jupyter_rfb event specification](https://jupyter-rfb.readthedocs.io/en/stable/events.html).
* Introduce the `auto` gui backend, which selects either glfw or jupyter.

Fixed:

* The wx gui backend is now fully functional.

Changed:

* The qt and wx gui backend now contain `WgpuCanvas` for a toplevel window,
and `WgpuWidget` for an embeddable widget.
* All gui backends (can) now limit the FPS.
* No changes to the wgpu API.

Fixed:

* Include the correct binaries in macOS arm64 wheels
* Options for arch argument of download-wgpu-native.py script

Added:

* Experimental support for macos_arm64 (M1).

Changed:

* The Qt examples use PySide6 instead of PyQt5.

Changed:

* Update to the latest wgpu-native (including latest Naga).
* The power-preference is actually taken into account.
* The adapter actually reports its limits.
* The limits in `request_device` are actually used.
* The `Adapter.is_software` property is renamed to `Adapter.is_fallback_adapter`.

Added:

* An offscreen canvas to take snapshots without needing a window.

Changed:

* On Windows, the Vulkan backend is now forced unless `WGPU_BACKEND_TYPE` is set.

Fixed:

* Better support for multiple canvases by fixing a specific Qt issue.
* Fixed that canvas was not passed to low level function of `request_adapter`.
* Support calling `get_current_texture()` multiple times during a draw.

Added:

* The wgpu backend can be forced using the `WGPU_BACKEND_TYPE` env variable.
Values can be e.g. "D3D12", "Metal", "Vulkan".
* Initial support for off-screen canvases.
* Adds `adapter.is_software` property.

Changed:

* The `GPUPresentationContext` class has been renamed to `GPUCanvasContext`.
* The functionality of the swap-chain has moved to the `GPUCanvasContext`.
* The now removed `GPUSwapChain` was used as a context manager. Instead,
the frame is presented (ala GL swapbuffers) automatically at the end of a draw.
* The `canvas.configure_swap_chain()` method has been removed. Instead,
`canvas.get_context()` should be used, to obtain a present/canvas context.
* The `adapter.request_device()` method has its arguments `non_guaranteed_features`
and `non_guaranteed_limits` replaced with `required_features` and `required_limits`.
* The enum field `StoreOp.clear` is now `StoreOp.discard`.
* The flag field `TextureUsage.SAMPLED ` is now `TextureUsage.TEXTURE_BINDING `.
* The flag field `TextureUsage.STORAGE ` is now `TextureUsage.STORAGE_BINDING `.
* The enum `InputStepMode` is now `VertexStepMode`.
* WGSL: `arrays` must be declared as `var` (not `let`) in order to allow dynamic indexing.
* WGSL: storage classes are written differently.