ibus-engines.table: 1.9.18 -> 1.9.20 (#40100)

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/k3qfsk06xxrm7sp4fwv7h5shdq7j1msk-ibus-table-1.9.20/bin/ibus-table-createdb -h’ got 0 exit code
- ran ‘/nix/store/k3qfsk06xxrm7sp4fwv7h5shdq7j1msk-ibus-table-1.9.20/bin/ibus-table-createdb --help’ got 0 exit code
- found 1.9.20 with grep in /nix/store/k3qfsk06xxrm7sp4fwv7h5shdq7j1msk-ibus-table-1.9.20
- directory tree listing: https://gist.github.com/ace63b0dd5941c9f17222549a08ee23c