Update Terraform tfe to ~> 0.64

Author: govuk-ci

terraform/deployments/elasticache/main.tf

@@ -13,7 +13,7 @@ terraform {
     }
     tfe = {
       source  = "hashicorp/tfe"
-      version = "~> 0.6"
+      version = "~> 0.64"
     }
   }
 }