Fix the issue which the media keys cannot be loaded.

boards/lunakey_pico/main.py

@@ -6,6 +6,7 @@ import time
 from kb import KMKKeyboard
 
 from kmk.extensions.RGB import RGB, AnimationModes
+from kmk.extensions.media_keys import MediaKeys
 from kmk.keys import KC
 from kmk.modules.layers import Layers
 from kmk.modules.modtap import ModTap
@@ -43,6 +44,7 @@ rgb_ext = RGB(
 )
 
 keyboard.modules = [layers_ext, modtap_ext, split]
+keyboard.extensions.append(MediaKeys())
 keyboard.extensions.append(rgb_ext)
 
 if split_side == SplitSide.LEFT: