PROTON_MEDIA_USE_GST=1 by default

data_from_portwine/scripts/functions_helper

@@ -3423,6 +3423,8 @@ start_portwine () {
         export STEAM_COMPAT_TRANSCODED_MEDIA_PATH="${PORT_WINE_TMP_PATH}/gstreamer_tmp"
         export MEDIACONV_AUDIO_DUMP_FILE="$STEAM_COMPAT_TRANSCODED_MEDIA_PATH/audiov2.foz"
         export MEDIACONV_VIDEO_DUMP_FILE="$STEAM_COMPAT_TRANSCODED_MEDIA_PATH/video.foz"
+
+        export PROTON_MEDIA_USE_GST="1"
     fi
 
     check_variables VKD3D_DEBUG "none"