Add builds with `\MD` flag for building Python extensions #299

Job	Run time
Run tests (windows-2019, x86_64, mingw64, true, -dbg)	19m 30s
Run tests (windows-2019, x86_64, mingw64, false)	15m 48s
Run tests (windows-2019, msvc-mt, mingw64, false, -mt)	24s
Run tests (windows-2022, msvc-mt, mingw64, false, -mt)	19s
Run tests (windows-2019, msvc-md, mingw64, false, -md)	24s
Run tests (windows-2022, msvc-md, mingw64, false, -md)	17s
	36m 42s

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