Require `requests` on Windows

As the web interface is needed on Windows (as there is no Curses
interface), make sure all of the web requirements are included on
Windows. This includes `bottle` (already listed) and `requests` (now
added).

setup.py

@@ -44,6 +44,7 @@ def get_install_requires():
     requires = ['psutil>=5.3.0']
     if sys.platform.startswith('win'):
         requires.append('bottle')
+        requires.append('requests')
 
     return requires