module: fix createRequireFromPath() slash logic

The trailing slash detection logic in createRequireFromPath()
seemed slightly incorrect. This commit reworks the logic.

PR-URL: https://github.com/nodejs/node/pull/27634
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Rich Trott <rtrott@gmail.com>

lib/internal/modules/cjs/loader.js

@@ -838,7 +838,7 @@ Module.runMain = function() {
 function createRequireFromPath(filename) {
   // Allow a directory to be passed as the filename
   const trailingSlash =
-    filename.endsWith(path.sep) || path.sep !== '/' && filename.endsWith('\\');
+    filename.endsWith('/') || (isWindows && filename.endsWith('\\'));
 
   const proxyPath = trailingSlash ?
     path.join(filename, 'noop.js') :