isocodes: 3.74 -> 3.79

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

This update was made based on information from https://repology.org/metapackage/iso-codes/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 3.79 with grep in /nix/store/v3cwlccrh7g5m03wj8j7fhwc9xyrdj1q-iso-codes-3.79
- directory tree listing: https://gist.github.com/0636a62cebb498fde2d51579ff9c3e99