Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.
This update was made based on information from https://repology.org/metapackage/ocaml4.05.0-yojson/versions.
These checks were done:
- built on NixOS
- ran `/nix/store/k3c6sbqahg7xbrraipzbbbvkrncfbb78-ocaml4.05.0-yojson-1.4.1/bin/ydump --help` got 0 exit code
- ran `/nix/store/k3c6sbqahg7xbrraipzbbbvkrncfbb78-ocaml4.05.0-yojson-1.4.1/bin/ydump --help` and found version 1.4.1
- found 1.4.1 with grep in /nix/store/k3c6sbqahg7xbrraipzbbbvkrncfbb78-ocaml4.05.0-yojson-1.4.1
- directory tree listing: https://gist.github.com/45ad3b6379841d4750efc7dcfe6b602f
adds myself as a maintainer
adds assertions to have evaluation errors rather than build errors
moves opam out of ocamlPackages, as it does not provide a library
