Mark Tails 3.5 as released.

debian/changelog

-tails (3.5) UNRELEASED; urgency=medium
+tails (3.5) unstable; urgency=medium
 
   * Security fixes
     - Upgrade amd64-microcode to 3.20171205.1, for the mitigation
@@ -40,7 +40,7 @@ tails (3.5) UNRELEASED; urgency=medium
     - Add a "Try cloning Tails to a too small partition" scenario
       (regression test for #14622).
 
- -- Tails developers <tails@boum.org>  Mon, 22 Jan 2018 22:40:45 +0100
+ -- Tails developers <tails@boum.org>  Tue, 23 Jan 2018 00:57:58 +0100
 
 tails (3.4) unstable; urgency=medium