Update to classes.py for windows container

[cricboy007]

I had to update line 131 in classes.py to proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True) to avoid ERROR - [WinError 2] The system cannot find the file specified error in windows container.

[eshaan7]

Hi, @cricboy007. In your cmd are you trying to expand an environment variable or something similar ? (reference)