libupnp: 1.6.21 -> 1.8.3

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 1.8.3 with grep in /nix/store/54dv1yd3bi54ci4kvlj9j7jc1khxm1ax-libupnp-1.8.3
- directory tree listing: https://gist.github.com/b72d1e3b6abc82c6c158d097f98780b9