MSOCI-1860: Change cidr_blocks value to list

base/nessus/instance_nessus_manager/securitygroup-server.tf

@@ -20,7 +20,7 @@ resource "aws_security_group" "nessus_manager" {
 resource "aws_security_group_rule" "nessus_manager_inbound_nessus" {
   security_group_id = aws_security_group.nessus_manager.id
   type              = "ingress"
-  cidr_blocks       = "10.0.0.0/8"
+  cidr_blocks       = ["10.0.0.0/8"]
   from_port         = 8834
   to_port           = 8834 # no 8835 according to https://docs.tenable.com/nessusagent/Content/RequirementsDataflow.htm
   protocol          = "tcp"