ibus-engines.table: 1.9.16 -> 1.9.18

Semi-automatic update generated by https://github.com/ryantm/nix-update tools. These checks were done:

- built on NixOS
- ran `/nix/store/mrix6kd1pgli5i7hji39f1pigx0d7s5z-ibus-table-1.9.18/bin/ibus-table-createdb -h` got 0 exit code
- ran `/nix/store/mrix6kd1pgli5i7hji39f1pigx0d7s5z-ibus-table-1.9.18/bin/ibus-table-createdb --help` got 0 exit code
- found 1.9.18 with grep in /nix/store/mrix6kd1pgli5i7hji39f1pigx0d7s5z-ibus-table-1.9.18
- directory tree listing: https://gist.github.com/8f2d6146d5348401ca9117762e2befbc