libunistring: 0.9.9 -> 0.9.10 (#41289)

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

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

These checks were done:

- built on NixOS

- 0 of 0 passed binary check by having a zero exit code.
- 0 of 0 passed binary check by having the new version present in output.
- found 0.9.10 with grep in /nix/store/riqyx0fb7ngq713fnpqb6ajhxkmngisd-libunistring-0.9.10
- directory tree listing: https://gist.github.com/9f56dbfdcfad3ced299ff55e6bce9e98
- du listing: https://gist.github.com/3f085a632b3b0ece77d88dcb5daf344e