not hardcode the ip allocation for agents

modules/host/main.tf

@@ -14,7 +14,7 @@ resource "hcloud_server" "server" {
 
   network {
     network_id = var.network_id
-    ip         = var.ip
+    ip         = try(var.ip, null)
   }
 
   connection {

modules/host/variables.tf

@@ -60,6 +60,7 @@ variable "network_id" {
 }
 
 variable "ip" {
+  default     = null
   description = "The IP"
   type        = string
   nullable    = true