Should build on Windows with Mingw

[ToniLipponen]

I agree that my contributions are licensed under the MIT License. Closes #60

[dacap]

Thanks @ToniLipponen for this, I'll take a look to this later. I would love to configure the GitHub actions to compile with MinGW too automatically to detect any kind of error, but I'm not aware of all the MinGW versions out there (or what is the "standard"/latest version).