Create CI target for `i686-pc-windows-msvc` on current windows

[elfenpiff]

Brief feature description

The platform is out of the box supported but some mistakes/bugs may occur when not using the right macro platform combination in c files. See #235 where we needed to use #if defined(_WIN32) || defined(_WIN64)

Since the 32-bit platform is already tested fully, a simple single debug build on Windows should be sufficient.