Synths - hide sound_in synths for this release

* Need to ensure they work on Win and RP first

Author: samaaron

app/server/sonicpi/lib/sonicpi/synths/synthinfo.rb

@@ -2906,7 +2906,7 @@ def user_facing?
       end
     end
 
-    class SoundIn < SonicPiSynth
+    class SoundIn < StudioInfo
       def name
         "Sound In"
       end