fix test

Author: cknitt

tests/build_tests/deprecated-package-specs/input.js

@@ -5,10 +5,10 @@ import { setup } from "#dev/process";
 
 const { execBuild, execClean } = setup(import.meta.dirname);
 
-const { stdout } = await execBuild();
+const { stderr } = await execBuild();
 
 assert.match(
-  stdout,
+  stderr,
   /deprecated: Option "es6-global" is deprecated\. Use "esmodule" instead\./,
 );