Remove unused unexported field

Author: fbiville

neo4j/auth_tokens.go

@@ -33,9 +33,6 @@ const keyPrincipal = "principal"
 const keyCredentials = "credentials"
 const keyRealm = "realm"
 
-// Deprecated: will be removed in 5.0. Use keyCredentials instead.
-const keyTicket = keyCredentials
-
 // NoAuth generates an empty authentication token
 func NoAuth() AuthToken {
 	return AuthToken{tokens: map[string]interface{}{