Add missing changelog entry.

debian/changelog

@@ -11,6 +11,8 @@ tails (3.0~beta3) UNRELEASED; urgency=medium
       at finding someone to maintain it in Tails (Closes: #12263).
 
   * Security fixes
+    - Upgrade MAT to 0.6.1-4: fixes silent failure of the Nautilus
+      contextual menu extension.
     - Ensure /etc/resolv.conf is owned by root:root in the SquashFS
       (Closes: #12343).
     - Protect against CVE-2017-2636 by disabling the n-hdlc kernel module