message: modify changelog for ubuntu
diff: seafile-gui (7.0.1) unstable; urgency=low
  * new upstream release
  --- Jonathan Xu <jonathan.xu@seafile.com> Tue, 9 July 2019 18:25:10 +0800
  + -- Jonathan Xu <jonathan.xu@seafile.com> Tue, 9 Jul 2019 18:25:10 +0800
  seafile-gui (7.0.0) unstable; urgency=low
  * new upstream release
  