trisquel-keyring: Make sure new keys are always processed

extra/trisquel-keyring/debian/changelog

+trisquel-keyring (2018.02.19) flidas; urgency=medium
+
+  * Make sure new keys are always processed
+
+ -- Trisquel GNU/Linux developers <trisquel-devel@listas.trisquel.info>  Mon, 19 Feb 2018 14:31:54 -0500
+
 trisquel-keyring (2017.01.07) flidas; urgency=medium
 
   * Added new key to fix #21407

extra/trisquel-keyring/debian/postinst

@@ -2,6 +2,7 @@
 
 # make sure apt knows about the new keys
 if [ -x /usr/bin/apt-key ]; then
+    /usr/bin/apt-key add /usr/share/keyrings/trisquel-archive-keyring.gpg
     /usr/bin/apt-key update
 fi