Update wgpu to v0.19.3 and unpin web-sys.

[xStrom]

wgpu used to depend on unstable web-sys features which don't follow SemVer. However things have changed, wgpu has now vendored those bindings. This was also backported and released as v0.19.3.

This means that pinning web-sys is no longer required. The following can be done:

• Update the wgpu requirement to 0.19.3.
• Remove the web-sys pin.

Doing so will unlock the ability for unrelated projects that have wgpu-profiler in their workspace to finally update their web-sys.

Also, an additional benefit of the aforementioned wgpu change is that wgpu no longer requires you to have --cfg=web_sys_unstable_apis in your RUSTFLAGS.

[Wumpf]

nice, thanks!