chirp: 20180519 -> 20180606 (#41717)

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

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

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/i289vfzp7kk8h7q27cxcyfsp92yjsgk6-chirp-daily-20180606/bin/.chirpw-wrapped had a zero exit code or showed the expected version
- Warning: no invocation of /nix/store/i289vfzp7kk8h7q27cxcyfsp92yjsgk6-chirp-daily-20180606/bin/chirpw had a zero exit code or showed the expected version
- 0 of 2 passed binary check by having a zero exit code.
- 0 of 2 passed binary check by having the new version present in output.
- found 20180606 with grep in /nix/store/i289vfzp7kk8h7q27cxcyfsp92yjsgk6-chirp-daily-20180606
- directory tree listing: https://gist.github.com/17376dee8e40c9f3de24818bb3278341
- du listing: https://gist.github.com/aefa3450ce2ed4ccd781360dc0a1de4e