balsa: 2.5.5 -> 2.5.6 (#42054)

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

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

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/1hgx73336q1zhd8r95wv2kicf6a2jmby-balsa-2.5.6/bin/balsa had a zero exit code or showed the expected version
- Warning: no invocation of /nix/store/1hgx73336q1zhd8r95wv2kicf6a2jmby-balsa-2.5.6/bin/balsa-ab had a zero exit code or showed the expected version
- Warning: no invocation of /nix/store/1hgx73336q1zhd8r95wv2kicf6a2jmby-balsa-2.5.6/bin/.balsa-wrapped had a zero exit code or showed the expected version
- Warning: no invocation of /nix/store/1hgx73336q1zhd8r95wv2kicf6a2jmby-balsa-2.5.6/bin/.balsa-ab-wrapped had a zero exit code or showed the expected version
- 0 of 4 passed binary check by having a zero exit code.
- 0 of 4 passed binary check by having the new version present in output.
- found 2.5.6 with grep in /nix/store/1hgx73336q1zhd8r95wv2kicf6a2jmby-balsa-2.5.6
- directory tree listing: https://gist.github.com/8c38ffd6950508c78fde54f6f3530673
- du listing: https://gist.github.com/2156c87e8b84b7a84f6d6f4c4a7b8ebb