Removes the stderr check to account for the experimental warning

Author: arcanis

test/es-module/test-esm-package-map.mjs

@@ -39,7 +39,6 @@ describe('ESM: --experimental-package-map', () => {
         `import dep from 'dep-a'; console.log(dep);`,
       ], { cwd: fixtures.path('package-map/root') });
 
-      assert.strictEqual(stderr, '');
       assert.match(stdout, /dep-a-value/);
       assert.strictEqual(code, 0);
     });