fix pinning

conf/etc_apt_preferences.d_zabbix

@@ -1,3 +1,7 @@
 Package: zabbix-*
-Pin: origin "repo.zabbix.com"
-Pin-Priority: 900
+Pin: origin repo.zabbix.com
+Pin-Priority: 900
+
+Package: zabbix-*
+Pin: origin security.debian.org
+Pin-Priority: -1