feh: 2.26 -> 2.26.1

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/n3q1mfdip3l49wx7dh293pwrxqhlrqgd-feh-2.26.1/bin/feh -h’ got 0 exit code
- ran ‘/nix/store/n3q1mfdip3l49wx7dh293pwrxqhlrqgd-feh-2.26.1/bin/feh --help’ got 0 exit code
- ran ‘/nix/store/n3q1mfdip3l49wx7dh293pwrxqhlrqgd-feh-2.26.1/bin/.feh-wrapped -h’ got 0 exit code
- ran ‘/nix/store/n3q1mfdip3l49wx7dh293pwrxqhlrqgd-feh-2.26.1/bin/.feh-wrapped --help’ got 0 exit code
- found 2.26.1 with grep in /nix/store/n3q1mfdip3l49wx7dh293pwrxqhlrqgd-feh-2.26.1
- directory tree listing: https://gist.github.com/1e8258220f00de69ea28c57fffe352aa
- du listing: https://gist.github.com/65e35fd7395eca9058de10721f96b7d3