weston: 3.0.0 -> 4.0.0

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/0354z3f09fdz91z0gypm630mwyyw9m6d-weston-4.0.0/bin/weston -h’ got 0 exit code
- ran ‘/nix/store/0354z3f09fdz91z0gypm630mwyyw9m6d-weston-4.0.0/bin/weston --help’ got 0 exit code
- ran ‘/nix/store/0354z3f09fdz91z0gypm630mwyyw9m6d-weston-4.0.0/bin/weston --version’ and found version 4.0.0
- ran ‘/nix/store/0354z3f09fdz91z0gypm630mwyyw9m6d-weston-4.0.0/bin/wcap-decode --help’ got 0 exit code
- found 4.0.0 with grep in /nix/store/0354z3f09fdz91z0gypm630mwyyw9m6d-weston-4.0.0
- directory tree listing: https://gist.github.com/01f9658faac9a7816ccf1ca44d11fe15