fix: use correct syntax to print list of Fail2Ban ignoreips as space separated string

tasks/configure_fail2ban.yml

@@ -29,7 +29,7 @@
 
       # ignored IPs: localhost, VLAN 20 (DV), sdvgubs10 (IP from multiple
       # subnets/VLANs), VPN IP ranges
-      ignoreip = 127.0.0.1/8 {{ vlans }} {{ vault_gubs_ips }} {{ vault_host_greenbone }}
+      ignoreip = 127.0.0.1/8 {{ vlans | join(" ") }} {{ gubs_ips | join(" ") }} {{ host_greenbone }}
 
       # number of failures that have to occur in the last findtime seconds to
       # ban then IP.