Fix MSVC build and CI tests

[will-v-pi]

Fix MSVC build, and add CI test of the MSVC build

Also fix the CI tests, as the UF2 files may now be ZIP files, so may need unzipping before use

[lurch]

I guess this partly overlaps with #289 ?

[will-v-pi]

I guess this partly overlaps with #289 ?

Yes, this fixes that issue the same way we have done for other files - I will merge this one first, as it adds CI tests which can test #289