fix HealthChange event name error

bot/event.go

@@ -8,7 +8,7 @@ type eventBroker struct {
 	GameStart    func() error
 	ChatMsg      func(msg chat.Message, pos byte) error
 	Disconnect   func(reason chat.Message) error
-	HealhtChange func() error
+	HealthChange func() error
 	Die          func() error
 	SoundPlay    func(name string, category int, x, y, z float64, volume, pitch float32) error
 }