postgresql: Allow access by IPv6

Since LAN clients have IPv6 addresses now, some may try to connect to
the database over IPv6, so we need to allow this in the host-based
authentication rules.

group_vars/postgresql.yml

@@ -33,6 +33,11 @@ pg_hba_extra:
   user: all
   address: 0.0.0.0/0
   method: cert
+- type: hostssl
+  database: sameuser
+  user: all
+  address: '::/0'
+  method: cert
 
 postgresql_restore_command: >-
   runuser -u postgres --