ccnet: 6.1.7 -> 6.1.8 (#40495)

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/ccnet/versions.

These checks were done:

- built on NixOS
- ran ‘/nix/store/k21v52qac99ppn2ba80ywki05cv6m65r-ccnet-6.1.8/bin/ccnet -h’ got 0 exit code
- ran ‘/nix/store/k21v52qac99ppn2ba80ywki05cv6m65r-ccnet-6.1.8/bin/ccnet --help’ got 0 exit code
- found 6.1.8 with grep in /nix/store/k21v52qac99ppn2ba80ywki05cv6m65r-ccnet-6.1.8
- directory tree listing: https://gist.github.com/275cfa6377f77e502dcc0309bb683687
- du listing: https://gist.github.com/f2f22837494355a9bf385b8432a4b210