Update neon_audio to include loosened dependency spec

requirements/core_modules.txt

@@ -3,7 +3,7 @@ neon_messagebus~=1.1
 neon_enclosure~=1.6
 neon_speech~=4.1,>=4.1.1a4
 neon_gui~=1.2,>=1.2.2
-neon_audio~=1.3,>=1.3.3a14
+neon_audio~=1.3,>=1.3.3a15
 
 # Troubleshooting version compat.
 ovos_plugin_common_play==0.0.6a2