Release of libvirt-5.5.0

* docs/news.xml: updated for the release
Signed-off-by: NDaniel Veillard <veillard@redhat.com>

docs/news.xml

@@ -39,7 +39,7 @@
      -->
 
 <libvirt>
-  <release version="v5.5.0" date="unreleased">
+  <release version="v5.5.0" date="2019-07-02">
     <section title="Security">
       <change>
         <summary>