Bump release date in announcement.

news/2018-briar-1.1-released.html

@@ -50,7 +50,7 @@
       <div id="content" class="news">
         <h3>Press Release</h3>
         <h2>Briar 1.1 released with dark theme, new emoji and more</h2>
-        <h5>September 13 2018</h5>
+        <h5>September 14 2018</h5>
 
         <p>
           The Briar Project released version 1.1 of its Android app today.