unbound: 1.7.0 -> 1.7.1

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/456crrnsgkrbicb54bwrwwl76n2645gq-unbound-1.7.1/bin/unbound-host help’ got 0 exit code
- found 1.7.1 with grep in /nix/store/456crrnsgkrbicb54bwrwwl76n2645gq-unbound-1.7.1
- directory tree listing: https://gist.github.com/ab82a0d52e5fd8bda918bbdaa6ce7609