feat: chat mute expiration timestamp (#351)

add chat.muteExpiration to indicate when the mute expires

Co-authored-by: Pedro S. Lopez <pedroslopez@me.com>

src/structures/Chat.js

@@ -57,6 +57,12 @@ class Chat extends Base {
          */
         this.archived = data.archive;
 
+        /**
+         * Unix timestamp for when the mute expires
+         * @type {number}
+         */
+        this.muteExpiration = data.muteExpiration;
+
         return super._patch(data);
     }