Include Windows ARM runners in testing

[awvwgk]

https://github.blog/changelog/2025-04-14-windows-arm64-hosted-runners-now-available-in-public-preview/

[henryiii]

This will probably not work out of the box; ilammy/msvc-dev-cmd#90 means this action will also have to pass in "arch: arm64" on Windows ARM when it calls that action.