CLI: Fix 'cd' subcommand on Windows (#16610)

The 'cd' subcommand was failing as the current shell's Windows path was
mangled while milc processed it.
Using 'subprocess' directly avoids this issue and an extra layer of
subshell.

lib/python/qmk/cli/cd.py

@@ -2,6 +2,7 @@
 """
 import sys
 import os
+import subprocess
 
 from milc import cli
 
@@ -41,6 +42,6 @@ def cd(cli):
             # Set the prompt for the new shell
             qmk_env['MSYS2_PS1'] = qmk_env['PS1']
             # Start the new subshell
-            cli.run([os.environ.get('SHELL', '/usr/bin/bash')], env=qmk_env)
+            subprocess.run([os.environ.get('SHELL', '/usr/bin/bash')], env=qmk_env)
     else:
         cli.log.info("Already within qmk_firmware directory.")