hgweb: remove unnecessary CDATA markup in atom/branchentry.tmpl

Since content is of type "text" (and is already escaped), using a CDATA section
is not required.

Looks like this was just an artifact of copying things from rss style in
add2f9ddcfb5, because other entries in atom style don't use CDATA in such
places.

mercurial/templates/atom/branchentry.tmpl

@@ -1,8 +1,8 b''
  <entry>
   <title>{branch|escape}</title>
   <link rel="alternate" href="{urlbase}{url|urlescape}rev/{node|short}"/>
   <id>{urlbase}{url|urlescape}#branch-{node}</id>
   <updated>{date|rfc3339date}</updated>
   <published>{date|rfc3339date}</published>
-  <content type="text"><![CDATA[{branch|strip|escape|addbreaks}]]></content>
+  <content type="text">{branch|strip|escape}</content>
  </entry>