Fix ineffassign and category json example (#120)

* Fix certificate test ineffassign
* Fix category json example

Author: sideshow

payload/builder.go

@@ -265,7 +265,7 @@ func (p *Payload) AlertSummaryArgCount(key int) *Payload {
 // This is a string value that represents the identifier property of the
 // UIMutableUserNotificationCategory object you created to define custom actions.
 //
-//	{"aps":{"alert":{"category":category}}}
+//	{"aps":{"category":category}}
 func (p *Payload) Category(category string) *Payload {
 	p.aps().Category = category
 	return p

token/token_test.go

@@ -86,7 +86,6 @@ func TestGenerateWithNoAuthKey(t *testing.T) {
 
 func TestGenerateWithInvalidAuthKey(t *testing.T) {
 	pubkeyCurve := elliptic.P521()
-	privatekey := &ecdsa.PrivateKey{}
 	privatekey, err := ecdsa.GenerateKey(pubkeyCurve, rand.Reader)
 
 	token := &token.Token{