Remove slash option type custom and add attachment

Author: Lulalaby

discord/enums.py

@@ -620,7 +620,7 @@ class SlashCommandOptionType(Enum):
     role = 8
     mentionable = 9
     number = 10
-    custom = 11
+    attachment = 11
 
     @classmethod
     def from_datatype(cls, datatype):
@@ -642,9 +642,6 @@ def from_datatype(cls, datatype):
         if issubclass(datatype, float):
             return cls.number
 
-        if hasattr(datatype, "convert"):
-            return cls.custom
-
         if datatype.__name__ == "Member":
             return cls.user
         if datatype.__name__ in [