Update to wgpu 0.20, fixing crashes with some linux setups (#6171)

### What

* Part of #6170
* Based on emilk/egui#4433
* Makes it possible to handle
#5968
* it no longer is a crash but an _okish_ error message (more to do
still)
 * Fixes #5283
    * [x] @jleibs can you confirm?


Test on:
* Mac
    * [x] native
    * [x] Firefox WebGL
    * [x] Chrome WebGPU
    * [x] Chrome WebGL 
* Windows
    * [x] native
    * [x] Firefox WebGL
    * [x] Chrome WebGPU
    * [x] Chrome WebGL 
* Linux
    * [x] native
    * [x] Firefox WebGL
    * [x] Chrome WebGPU
* needs both chrome://flags/#enable-unsafe-webgpu &
chrome://flags/#enable-vulkan flags set (via
https://developer.chrome.com/docs/web-platform/webgpu/troubleshooting-tips)
    * [x] Chrome WebGL 

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using examples from latest `main` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6171?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6171?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/6171)
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