tini: 0.17.0 -> 0.18.0

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/h0h2qyxwrvsjy47m1xyv7sxzd2j0ilsi-tini-0.18.0/bin/tini -h’ got 0 exit code
- ran ‘/nix/store/h0h2qyxwrvsjy47m1xyv7sxzd2j0ilsi-tini-0.18.0/bin/tini --version’ and found version 0.18.0
- found 0.18.0 with grep in /nix/store/h0h2qyxwrvsjy47m1xyv7sxzd2j0ilsi-tini-0.18.0
- directory tree listing: https://gist.github.com/c992fd0a24dfc0365d6b62ac567d395c