palemoon: 27.8.0 -> 27.8.3

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

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

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 27.8.3 with grep in /nix/store/jnhd2rzskaad61xh3d3rs63hjy8cwi7y-palemoon-27.8.3
- directory tree listing: https://gist.github.com/97a439e8880c3937586c5d06a2ac0844