Mark Tails 4.2.2 as released.

debian/changelog

-tails (4.2.2) UNRELEASED; urgency=medium
+tails (4.2.2) unstable; urgency=medium
 
   * Major changes
     - Upgrade Tor Browser to 9.0.4-build1 (MFSA-2020-03)
@@ -15,7 +15,7 @@ tails (4.2.2) UNRELEASED; urgency=medium
       owned by root, otherwise an upgraded system cannot start
       (Closes: #17422)
 
- -- Tails developers <tails@boum.org>  Thu, 09 Jan 2020 17:09:15 +0100
+ -- Tails developers <tails@boum.org>  Mon, 13 Jan 2020 09:21:51 +0000
 
 tails (4.2) unstable; urgency=medium