[zanata] Update Zanata URL

zanata.xml

 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <config xmlns="http://zanata.org/namespace/config/">
-  <url>https://trad.framasoft.org/zanata/</url>
+  <url>https://trad.framasoft.org/</url>
   <project>framadate</project>
   <project-version>master</project-version>
   <project-type>gettext</project-type>