flarum info: Try to fix STDERR redirection for Windows

See the following articles for more information:
- https://www.24k.com.sg/blog-27.html
- https://support.microsoft.com/en-us/help/110930/redirecting-error-messages-from-command-prompt-stderr-stdout

Refs #1562.

framework/core/src/Foundation/Console/InfoCommand.php

@@ -116,7 +116,7 @@ class InfoCommand extends AbstractCommand
 
             $output = [];
             $status = null;
-            exec('git rev-parse HEAD 2> /dev/null', $output, $status);
+            exec('git rev-parse HEAD 2>&1', $output, $status);
 
             chdir($cwd);