gnused: 4.4 -> 4.5

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

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

These checks were done:

- built on NixOS
- ran `/nix/store/71dzrirkbkpna9l1mcbjjhdws2y1g1hj-gnused-4.5/bin/sed --help` got 0 exit code
- ran `/nix/store/71dzrirkbkpna9l1mcbjjhdws2y1g1hj-gnused-4.5/bin/sed --version` and found version 4.5
- ran `/nix/store/71dzrirkbkpna9l1mcbjjhdws2y1g1hj-gnused-4.5/bin/sed --help` and found version 4.5
- found 4.5 with grep in /nix/store/71dzrirkbkpna9l1mcbjjhdws2y1g1hj-gnused-4.5
- directory tree listing: https://gist.github.com/20a2031e4b27616ba71439622e5fe4d1