miniupnpd: 2.0.20180503 -> 2.1

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

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

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 2.1 with grep in /nix/store/1gdrqzzksdxk4vnbgaa2zlsvyx1qdn7h-miniupnpd-2.1
- directory tree listing: https://gist.github.com/033415d078a1ec6d4641ed723b27e29b