MSVC support is broken in Github Actions

[eliasdaler]

@pinam45, can you please take a look at this?
Example where this is broken:

https://github.com/eliasdaler/imgui-sfml/actions/runs/2055442870

I've removed MSVC builds in master for now - if someone knows how to fix them, I'll be glad to merge a PR (a bit busy IRL at the moment, can't spend time looking at it myself, sorry...)

[pinam45]

Hi, I will take a look at it.