remove --impure from upd.py

now that I'm not on xonsh, my config is no longer known impure, and I'd
like warnings when I do something unpure

scripts/py/upd.py

@@ -84,8 +84,6 @@ def _upd(
             )
             run(["rm", "-rf", ".vscode/extensions"], cwd="/home/cswimr")
         print(f"{c.BLUE}Rebuilding {c.YELLOW}NixOS{c.BLUE} configuration{c.END}")
-        # TODO: Remove --impure once the Starship module is merged - see ../../nixos/shell.nix for more information
-        extra_args.append("--impure")
         if "--impure" in extra_args:
             print(f"{c.RED}WARNING: The --impure flag is set!{c.END}")
         run(["sudo", "nixos-rebuild", subcommand, *extra_args], cwd=path)