test: fix child-process-uid-gid on Windows

The process.getuid method does not exist on this platform.

Ref: #8864
PR-URL: #8924
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Wyatt Preul <wpreul@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-child-process-uid-gid.js

@@ -3,7 +3,7 @@ const common = require('../common');
 const assert = require('assert');
 const spawn = require('child_process').spawn;
 
-if (process.getuid() === 0) {
+if (!common.isWindows && process.getuid() === 0) {
   common.skip('as this test should not be run as `root`');
   return;
 }