Fix: refresh message authentication when serialising

src/pyrad3/packet.py

@@ -183,6 +183,8 @@ class Packet(OrderedDict):
 
     def serialize(self) -> bytes:
         """Serialize the Packet to the RADIUS Line Format"""
+        if self.host.message_authenticator:
+            self.add_message_authenticator()
         # TODO: This is not an abstract method
         raise NotImplementedError
 
@@ -298,17 +300,12 @@ class AcctPacket(Packet):  # pylint: disable=abstract-method
     def increase_acct_delay_time(self, delay_time: float):
         """Increase the Accounting Delay Time
 
-        This method automatically adjust the Authenticator
-        and the Message-Authenticator (if present)
-
         No check for the Accounting Codes are made, an
         Accounting-Respones should not contain the
         Acct-Delay-Time Attribute.
         """
         try:
             self["Acct-Delay-Time"] += int(delay_time)
-            if self.host.message_authenticator:
-                self.refresh_message_authenticator()
         except KeyError:
             pass