dialog: 1.3-20171209 -> 1.3-20180621 (#42512)

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

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

These checks were done:

- built on NixOS
- /nix/store/m0hxh556s4yrr5m1sdbj1hr4kghms99x-dialog-1.3-20180621/bin/dialog passed the binary check.
- 1 of 1 passed binary check by having a zero exit code.
- 1 of 1 passed binary check by having the new version present in output.
- found 1.3-20180621 with grep in /nix/store/m0hxh556s4yrr5m1sdbj1hr4kghms99x-dialog-1.3-20180621
- directory tree listing: https://gist.github.com/a0a4bc59b6cd5033a62a99d509b6903e
- du listing: https://gist.github.com/fd4c8d60fa9ed0c6f0fb56fdaf3f8b2b