fix: Prevent parallel test execution for busybox_ar_fallback

Add serial_test dependency and use #[serial] attribute to ensure
the busybox_ar_fallback test runs serially, not in parallel with
other tests. This prevents cross-contamination where the custom
ar/ranlib scripts from this test interfere with other tests running
concurrently in CI.

Fixes CI failures where tests tried to write to directories belonging
to other test instances.

Author: naoNao89

Cargo.toml

@@ -37,6 +37,7 @@ jobserver = []
 
 [dev-dependencies]
 tempfile = "3"
+serial_test = "3"
 
 [workspace]
 members = [

tests/busybox_ar_fallback.rs

@@ -4,10 +4,12 @@
 #![allow(clippy::disallowed_methods)]
 
 use crate::support::Test;
+use serial_test::serial;
 
 mod support;
 
 #[test]
+#[serial]
 fn busybox_ar_fallback() {
     // Use standard test setup with proper cc-shim
     let test = Test::gnu();