x509-cert: rustfmt limbo.rs imports

Move the `Certificate` re-export ahead of the `der` and `ext` modules
in the `use x509_cert { ... }` group so `cargo fmt --all -- --check`
passes. Pure formatting; no behavior change.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: tob-scott-a

x509-cert/tests/limbo.rs

@@ -10,9 +10,9 @@ use std::{
 use serde::Deserialize;
 use serde_json::Value;
 use x509_cert::{
+    Certificate,
     der::{Decode, Document, Encode},
     ext::pkix::{BasicConstraints, ExtendedKeyUsage, KeyUsage, NameConstraints, SubjectAltName},
-    Certificate,
 };
 
 #[derive(Debug, Deserialize)]