confclerk: 0.6.1 -> 0.6.4

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

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

These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 0.6.4 with grep in /nix/store/r8p6g80aawh16ixw0f29k3y88z3gjwkh-confclerk-0.6.4
- directory tree listing: https://gist.github.com/bc73c35c3cf2429de20668a18ae13885