Fixed error building DOM toggle_chats.html span.unread-message-count class attribute (#960)

* Added missing " on class attribute

* Added changelog for prev commit "Added missing " on class attribute"

CHANGES.md

@@ -15,6 +15,7 @@
   Otherwise connected contacts might not get your presence updates.
 - The way the archive ID of a MAM message is specified, has changed.
   See https://xmpp.org/extensions/xep-0313.html#archives_id
+- Fixed error building DOM toggle_chats.html span.unread-message-count class attribute
 
 ### New Features
 - #314 Add support for opening chat rooms with a URL fragment such as `#converse/room?jid=room@domain`

src/templates/toggle_chats.html

 {{{o.Minimized}}} <span id="minimized-count">({{{o.num_minimized}}})</span>
 <span class="unread-message-count
-    {[ if (!o.num_unread) { ]} unread-message-count-hidden {[ } ]}
+    {[ if (!o.num_unread) { ]} unread-message-count-hidden {[ } ]}"
     href="#">{{{o.num_unread}}}</span>