Add content_type to Attachment

Author: Zomatree

discord/message.py

@@ -111,9 +111,13 @@ class Attachment(Hashable):
         The proxy URL. This is a cached version of the :attr:`~Attachment.url` in the
         case of images. When the message is deleted, this URL might be valid for a few
         minutes or not valid at all.
+    content_type: Optional[:class:`str`]
+        The attachment's `media type <https://en.wikipedia.org/wiki/Media_type>`_
+
+        .. versionadded: 1.7
     """
 
-    __slots__ = ('id', 'size', 'height', 'width', 'filename', 'url', 'proxy_url', '_http')
+    __slots__ = ('id', 'size', 'height', 'width', 'filename', 'url', 'proxy_url', '_http', 'content_type')
 
     def __init__(self, *, data, state):
         self.id = int(data['id'])
@@ -124,6 +128,7 @@ def __init__(self, *, data, state):
         self.url = data.get('url')
         self.proxy_url = data.get('proxy_url')
         self._http = state.http
+        self.content_type = data.get('content_type')
 
     def is_spoiler(self):
         """:class:`bool`: Whether this attachment contains a spoiler."""