feh: 2.26.3 -> 2.26.4

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
- /nix/store/81pgn9ww37hp996d45xrm9wbl6z8wfc3-feh-2.26.4/bin/feh passed the binary check.
- /nix/store/81pgn9ww37hp996d45xrm9wbl6z8wfc3-feh-2.26.4/bin/.feh-wrapped passed the binary check.
- 2 of 2 passed binary check by having a zero exit code.
- 0 of 2 passed binary check by having the new version present in output.
- found 2.26.4 with grep in /nix/store/81pgn9ww37hp996d45xrm9wbl6z8wfc3-feh-2.26.4
- directory tree listing: https://gist.github.com/13a57ff84731135ece55fe0c99093a7d
- du listing: https://gist.github.com/dda79019b9ca9069b6dd9dbb773bf602