rawtherapee: 5.3 -> 5.4

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 5.4 with grep in /nix/store/p24xccx2wm6dls7g36pzdl1m1r3p1x5l-rawtherapee-5.4
- directory tree listing: https://gist.github.com/ea61efad6dd7afad2c60614dd433534d