Nixpkgs PR #285828 ("build-support/php: set `COMPOSER_ROOT_VERSION` environment variable") progress

✅PR #285828 ("build-support/php: set `COMPOSER_ROOT_VERSION` environment variable")
✅ master
- ✅ nixpkgs-unstable
- ✅ nixos-unstable-small
  - ✅ nixos-unstable