ci : add BUILD_SHARED_LIBS=ON windows build option

Author: danbev

.github/workflows/build.yml

@@ -559,6 +559,7 @@ jobs:
         run: >
           cmake -S . -B ./build -A ${{ matrix.arch }}
           -DCMAKE_BUILD_TYPE=${{ matrix.build }}
+          -DBUILD_SHARED_LIBS=ON
           -DWHISPER_SDL2=${{ matrix.sdl2 }}
 
       - name: Build