Modify CMAKE_FLAGS for mingw32 in windows.yml #1285

Job	Run time
🔧 MSVC Additional (static_lib)	2m 12s
🔨 MSVC x86 cpp11	2m 31s
🔨 MSVC x86 glib	2m 29s
🔨 MSVC x64 cpp11	2m 32s
🔧 MSVC Additional (no_network)	2m 47s
🔧 MinGW fluidsynth-mingw2 x86	1m 33s
🚧🟦 mingw64 cpp11	3m 46s
🔧 MinGW fluidsynth-mingw-ffloat-store x86	1m 35s
🚧🟨 ucrt64 cpp11	3m 51s
🚧🟧 clang64 glib	4m 44s
🔨 MSVC x64 glib	2m 26s
🚧🟧 clang64 cpp11	3m 44s
🔧 MinGW fluidsynth-mingw1 x86	2m 46s
🔧 MinGW fluidsynth-mingw x86	1m 31s
🚧⬛ mingw32 cpp11	3m 30s
🔧 MSVC Additional (default)	2m 18s
🔧 MSVC Additional (osal_cpp11)	2m 22s
🚧🟨 ucrt64 glib	3m 41s
🚧⬛ mingw32 glib	3m 24s
🔧 MinGW fluidsynth-mingw x64	1m 54s
🔧 MinGW fluidsynth-mingw-static x64	1m 53s
🚧🟦 mingw64 glib	4m 14s
🔧 MSVC Additional (debug_prof)	2m 17s
🔧 MSVC Additional (minimal)	2m 12s
🧪 Acceptance Test	-1s
📢 Announce Release	-1s
🚀 Publish Release Artifacts	-1s
	1h 6m 9s

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