Update changelog for 3.7.

debian/changelog

 tails (3.7) UNRELEASED; urgency=medium
 
-  * Dummy entry for next release.
+  * Security fixes
+    - Upgrade Tor Browser to 7.5.4 (MFSA 2018-11, Closes: #15588).
+    - Upgrade OpenSSL to 1.1.0f-3+deb9u2 (DSA-4157).
+    - Upgrade Perl to 5.24.1-3+deb9u3 (DSA-4172).
+    - Upgrade Libre Office to 1:5.2.7-1+deb9u4 (DSA-4178).
+    - Upgrade libmad to 0.15.1b-8+deb9u1 (DSA-4192).
+
+  * Bugfixes
+    - Enable the removal of OpenPGP keyblock in Whisperback (closes: #7797).
+    - Show the logo in Whisperback's About menu (closes: #13198).
+    - Use the same font in all the Whisperback report (Closes: #11272).
+
+  * Minor improvements
+    - Stop installing python-qt4 and python-trezor (Closes: #15391).
+    - Make WhisperBack easier to find in the GNOME Overview (Closes: #13299).
 
- -- Tails developers <tails@boum.org>  Fri, 30 Mar 2018 18:46:33 +0200
+ -- Tails developers <tails@boum.org>  Mon, 07 May 2018 22:38:54 +0200
 
 tails (3.6.2) unstable; urgency=medium