Remove defaults, use defaults at server instead

action.yml

@@ -10,11 +10,9 @@ inputs:
   priority:
     description: 'Message priority'
     required: false
-    default: '0'
   sound:
     description: 'Sound to play'
     required: false
-    default: 'pushover'
   title:
     description: 'Message title'
     required: false