cli: Fix small typo ("f{arg} -> f"{arg})

Author: colinoflynn

software/glasgow/cli.py

@@ -375,7 +375,7 @@ def factory_manufacturer(arg):
         if len(arg) <= 23:
             return arg
         else:
-            raise argparse.ArgumentTypeError("f{arg} is too long for the manufacturer field")
+            raise argparse.ArgumentTypeError(f"{arg} is too long for the manufacturer field")
 
     p_factory = subparsers.add_parser(
         "factory", formatter_class=TextHelpFormatter,