var names were incorrect

dev/main.tf

@@ -65,5 +65,5 @@ variable "cluster_name" {
 resource "azurerm_role_assignment" "kubweb_to_acr" {
   scope                = azurerm_container_registry.acr[count.index].acr.id
   role_definition_name = "AcrPull"
-  principal_id         = azurerm_kubernetes_cluster.kubweb.kubelet_identity[0].object_id
+  principal_id         = azurerm_kubernetes_cluster.identity.kubelet_identity[0].object_id
 }