gitlab: fix archive urls for gitlab service

Accessing an url like https://gitlab.example.org/group/project/repository/archive.tar.gz?ref=master
requires tar/gzip to be in the path of the gitlab-workhorse service otherwise it fails.

Changed files
+2
nixos
modules
services
misc
+2
nixos/modules/services/misc/gitlab.nix
···
environment.GITLAB_SHELL_CONFIG_PATH = gitlabEnv.GITLAB_SHELL_CONFIG_PATH;
path = with pkgs; [
gitAndTools.git
+
gnutar
+
gzip
openssh
gitlab-workhorse
];