fix timestamp issue

packages/mastodon/mastodon.js

@@ -129,7 +129,7 @@
 			}
 			
 			const user = json.account.username + "@" + _converse.connection.domain;				
-			const time = dayjs(json.created_at).format('MMM DD YYYY HH:mm:ss');	
+			const time = dayjs(json.created_at).format('YYYY-MM-DDTHH:mm:ssZ');
 			const msgId = json.id;
 			const title = json.account.display_name.trim() == "" ? json.account.username : json.account.display_name;
 			const avatar = json.account.avatar_static;