Enable project and volume usage to be optional, off by default, unless the use_project and use_volume variables are set to a positive number

resource.digitalocean_volume.this.tf

@@ -1,8 +1,7 @@
 resource "digitalocean_volume" "this" {
-  count                   = var.volume_size > 1 ? 1 : 0
-  description             = "Data Volume for ${var.host_name}.${var.domain_name}"
-  initial_filesystem_type = "ext4"
-  name                    = var.host_name
-  region                  = var.region
-  size                    = var.volume_size
+  count       = var.use_volume > 0 ? 1 : 0
+  description = "Data Volume for ${var.host_name}.${var.domain_name}"
+  name        = var.host_name
+  region      = var.region
+  size        = var.volume_size
 }