nixos/gitlab: Add gnutar and gzip to gitlab-sidekiq's path

Tar and gzip are needed when importing GitLab project exports.

(cherry picked from commit aceac9d531b72a49546f743ef96ee515770295c9)

nixos/modules/services/misc/gitlab.nix

···
         openssh
         nodejs
         gnupg
+
+        # Needed for GitLab project imports
+        gnutar
+        gzip
       ];
       serviceConfig = {
         Type = "simple";