Fix requiredFeatureCount struct assignment

[JeffreyPalmer]

I noticed that there was a warning in the repl logs when running the triangle example about setting a non-existent struct field. I fixed it by replacing the assignment to requiredFeaturesCount with requiredFeatureCount, as is in the WebGPU header.

Thanks for your work on this!

[arhik]

@JeffreyPalmer check fails are not related to your PR.

Note for later reference:
Checks are done against master (dev) branch as per CI.yml. But currently Core is lagging behind and is using WGPUNative v0.1.4. Fix is to somehow make CI to use compatible WGPUNative version. It will also be good move for future checks.