gnustep-make: 2.6.8 -> 2.7.0

Semi-automatic update generated by https://github.com/ryantm/nix-update tools. These checks were done:

- built on NixOS
- ran `/nix/store/9bilynlmzsc8z4wv6qjpgz983r434yad-gnustep-make-2.7.0/bin/gnustep-tests -h` got 0 exit code
- ran `/nix/store/9bilynlmzsc8z4wv6qjpgz983r434yad-gnustep-make-2.7.0/bin/gnustep-tests --help` got 0 exit code
- ran `/nix/store/9bilynlmzsc8z4wv6qjpgz983r434yad-gnustep-make-2.7.0/bin/gnustep-tests -h` and found version 2.7.0
- ran `/nix/store/9bilynlmzsc8z4wv6qjpgz983r434yad-gnustep-make-2.7.0/bin/gnustep-tests --help` and found version 2.7.0
- ran `/nix/store/9bilynlmzsc8z4wv6qjpgz983r434yad-gnustep-make-2.7.0/bin/openapp --help` got 0 exit code
- ran `/nix/store/9bilynlmzsc8z4wv6qjpgz983r434yad-gnustep-make-2.7.0/bin/opentool --help` got 0 exit code
- ran `/nix/store/9bilynlmzsc8z4wv6qjpgz983r434yad-gnustep-make-2.7.0/bin/gnustep-config --help` got 0 exit code
- found 2.7.0 with grep in /nix/store/9bilynlmzsc8z4wv6qjpgz983r434yad-gnustep-make-2.7.0
- directory tree listing: https://gist.github.com/30c82119c95760404469e4a1fcfa0d8d