Document changes and release 1:78.9.0-1

debian/changelog

+thunderbird (1:78.9.0-1) unstable; urgency=medium
+
+  [ Colomban Wendling ]
+  * [7d454de] d/thunderbird.desktop: Switch StartupWMClass
+    (Closes: #985366)
+
+  [ Carsten Schoenert ]
+  * [23fe9ce] d/source.filter: small update to filtering list
+  * [828b9d7] New upstream version 78.9.0
+    Fixed CVE issues in upstream version 78.9 (MFSA 2021-12):
+    CVE-2021-23981: Texture upload into an unbound backing buffer resulted in
+                    an out-of-bound read
+    CVE-2021-23982: Internal network hosts could have been probed by a
+                    malicious webpage
+    CVE-2021-23984: Malicious extensions could have spoofed popup information
+    CVE-2021-23987: Memory safety bugs fixed in Thunderbird 78.9
+  * [cf4fbde] rebuild patch queue from patch-queue branch
+    Removed patch (included upstream):
+    porting-s390x/Explicitly-instantiate-TIntermTraverser-traverse-TIntermN.patch
+
+ -- Carsten Schoenert <c.schoenert@t-online.de>  Tue, 23 Mar 2021 15:55:43 +0100
+
 thunderbird (1:78.8.0-1) unstable; urgency=medium
 
   [ Pino Toscano ]