libidn2: 2.0.4 -> 2.0.5 (#40852)

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

This update was made based on information from https://repology.org/metapackage/libidn2/versions.

These checks were done:

- built on NixOS
- /nix/store/lqhvipkml1hdjrc7x44a9qx6ib3h7fk4-libidn2-2.0.5-bin/bin/idn2 passed the binary check.
- 1 of 1 passed binary check by having a zero exit code.
- 0 of 1 passed binary check by having the new version present in output.
- found 2.0.5 with grep in /nix/store/lqhvipkml1hdjrc7x44a9qx6ib3h7fk4-libidn2-2.0.5-bin
- directory tree listing: https://gist.github.com/e275c93b988cd78a7716800d30d6d315
- du listing: https://gist.github.com/d80481a1635867ebfce278bd1e58d900