pius: 2.2.4 -> 2.2.6

Semi-automatic update generated by https://github.com/ryantm/nix-update tools. 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 2.2.6 with grep in /nix/store/q9ca3k22liz3dsaipnlnw8fmggpqx1n1-pius-2.2.6
- directory tree listing: https://gist.github.com/0d14ff30c172f091a342653aae676f55