ci: create wine prefix in build directory

to avoid `wine: '/github/home' is not owned by you, refusing to create a configuration directory there` error

Author: awaken1ng

.github/workflows/ci.yml

@@ -28,6 +28,8 @@ jobs:
           submodules: 'recursive'
 
       - run: |
+          export WINEPREFIX=.wine
+          mkdir $WINEPREFIX
           cmake -B build build -DBUILD_PS2=1 -DBUILD_ARM=0 -DBOARD=waveshare-rp2040-tiny
           cmake --build build