fix(e2e): add missing serial_test import in replication_extension_test

Commit 1cf0f7af1 added 6 #[serial] attributes to new SSE-C and
proxy-read replication tests but omitted the required
'use serial_test::serial' import, causing clippy to fail with
'cannot find attribute serial in this scope'.

crates/e2e_test/src/replication_extension_test.rs

@@ -60,6 +60,7 @@ use rustfs_signer::constants::UNSIGNED_PAYLOAD;
 use rustfs_signer::sign_v4;
 use s3s::Body;
 use s3s::header::X_AMZ_REPLICATION_STATUS;
+use serial_test::serial;
 use sha2::{Digest, Sha256};
 use std::collections::BTreeMap;
 use std::convert::Infallible;