Update distro versions (-16.04, +21.10)

Change-Id: Ie4a2e398eeab1cc5aab6b42349180d3dbf2b73dd
diff --git a/packaging.mk b/packaging.mk
index 9bde453..661bd98 100644
--- a/packaging.mk
+++ b/packaging.mk
@@ -2,7 +2,7 @@
 PPA=ppa:named-data/ppa-dev
 
 # List of target distributions
-DISTROS=xenial bionic focal
+DISTROS=bionic focal impish
 
 DEBUILD=debuild -S -d