Fixed code not compliant with a new flake8 CI check

Signed-off-by: jakub-nt <175944085+jakub-nt@users.noreply.github.com>

Author: jakub-nt

cfbs/commands.py

@@ -87,15 +87,13 @@ def __init__(self, message):
 # Does not modify/wrap the function it decorates.
 def cfbs_command(name):
     def inner(function):
-        global _commands
         _commands[name] = function
         return function  # Unmodified, we've just added it to the dict
 
     return inner
 
 
 def get_command_names():
-    global _commands
     names = _commands.keys()
     return names