libidn: 1.33 -> 1.34

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

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

These checks were done:

- built on NixOS
- ran `/nix/store/0i5mh79ayn9s5hzk33qc4r46iv6vq39b-libidn-1.34-bin/bin/idn -h` got 0 exit code
- ran `/nix/store/0i5mh79ayn9s5hzk33qc4r46iv6vq39b-libidn-1.34-bin/bin/idn --help` got 0 exit code
- ran `/nix/store/0i5mh79ayn9s5hzk33qc4r46iv6vq39b-libidn-1.34-bin/bin/idn help` got 0 exit code
- ran `/nix/store/0i5mh79ayn9s5hzk33qc4r46iv6vq39b-libidn-1.34-bin/bin/idn -V` and found version 1.34
- ran `/nix/store/0i5mh79ayn9s5hzk33qc4r46iv6vq39b-libidn-1.34-bin/bin/idn --version` and found version 1.34
- ran `/nix/store/0i5mh79ayn9s5hzk33qc4r46iv6vq39b-libidn-1.34-bin/bin/idn -h` and found version 1.34
- ran `/nix/store/0i5mh79ayn9s5hzk33qc4r46iv6vq39b-libidn-1.34-bin/bin/idn --help` and found version 1.34
- found 1.34 with grep in /nix/store/0i5mh79ayn9s5hzk33qc4r46iv6vq39b-libidn-1.34-bin
- directory tree listing: https://gist.github.com/2097e7f4c50acbee75a30738c68f417c