Allow to execute update script in CI environment
Allow to execute update script in CI environment

If the script is executed in a CI (like in github actions, with the
install-nix-action) it fails. This changes fixes that use case. In that
scenario, you should provide the --no-commit flag.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs