heroku: 7.16.0 -> 7.18.2

* heroku: 7.16.0 -> 7.18.2 (#50096)

Semi-automatic update generated by
https://github.com/ryantm/nixpkgs-update tools. This update was made
based on information from
https://repology.org/metapackage/heroku/versions

* heroku: split native build inputs