remove botch isoformat on embed method

disco/api/client.py

@@ -165,7 +165,7 @@ class APIClient(LoggingClass):
             payload['content'] = content
 
         if embed:
-            payload['embed'] = embed.to_dict(iso=True)
+            payload['embed'] = embed.to_dict()
 
         if attachments:
             if len(attachments) > 1:
@@ -197,7 +197,7 @@ class APIClient(LoggingClass):
             payload['content'] = content
 
         if embed:
-            payload['embed'] = embed.to_dict(iso=True)
+            payload['embed'] = embed.to_dict()
 
         r = self.http(Routes.CHANNELS_MESSAGES_MODIFY,
                       dict(channel=channel, message=message),

disco/types/message.py

@@ -4,8 +4,6 @@ import warnings
 import functools
 import unicodedata
 
-from datetime import datetime as real_datetime
-
 from disco.types.base import (
     SlottedModel, Field, ListField, AutoDictField, snowflake, text,
     datetime, enum, cached_property,
@@ -330,14 +328,6 @@ class MessageEmbed(SlottedModel):
         """
         self.fields.append(MessageEmbedField(*args, **kwargs))
 
-    def to_dict(self, iso=False):
-        data = super(MessageEmbed, self).to_dict()
-        # Ensure api calls don't try to send a non-json serializable datetime object.
-        if iso and isinstance(data.get("timestamp"), real_datetime):
-            data["timestamp"] = data["timestamp"].isoformat()
-
-        return data
-
 
 class MessageAttachment(SlottedModel):
     """