Update terraform backend config (use directly from env)

main.tf

@@ -18,7 +18,7 @@ terraform {
     }
     scaleway = {
       source = "scaleway/scaleway"
-      version = "~> 2.43.0"
+      version = "~> 2.53.0"
     }
     tailscale = {
       source = "tailscale/tailscale"
@@ -41,14 +41,8 @@ terraform {
 
   backend "s3" {
     bucket         = var.backend_bucket
-    access_key     = var.backend_access_key
-    secret_key     = var.backend_secret_key
     key            = "terraform.tfstate"
-    region         = var.backend_region
     encrypt        = true
-    endpoints      = {
-      s3           = var.backend_endpoint
-    }
 
     # Disable AWS-specific features
     skip_credentials_validation = true