fix: --force-color command line argument overrides NO_COLOR envir…

…onment variable (#723)

Change function to support behavior from issue
"--force-color should override NO_COLOR in the containing environment"

nox/_options.py

@@ -181,7 +181,7 @@ def _color_finalizer(value: bool, args: argparse.Namespace) -> bool:
     if args.forcecolor:
         return True
 
-    if args.nocolor:
+    if args.nocolor or "NO_COLOR" in os.environ:
         return False
 
     return sys.stdout.isatty()