chore: add update-input recipe

Changed files
+3
+3
justfile
···
@echo "Running utils/{{recipe}}"
@cd utils && just {{recipe}}
+
update-input input:
+
nix flake lock --update-input {{input}}
+
ebuild system:
nix build -j8 .#nixosConfigurations."{{system}}".config.system.build.toplevel