roles/common: Update apt in firewall task

Otherwise the buster-backports source might not be available, as
the nightly security upates use a different apt sources.list.

roles/common/tasks/firewall_Debian.yml

@@ -3,7 +3,7 @@
 - block:
   - name: Install iptables 1.8.3 on Debian Buster
     when: ansible_distribution_major_version is version_compare('10', '==')
-    apt: pkg=iptables state=present default_release=buster-backports
+    apt: pkg=iptables state=present default_release=buster-backports update_cache=yes cache_valid_time=3600
 
   - name: Install firewalld and deps
     when: ansible_distribution_major_version is version_compare('8', '>=')