insomnia: 5.16.2 -> 5.16.6

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

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

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/98c4q9sy1qvxivk5f5svimhm4q6il3d9-insomnia-5.16.6/bin/.insomnia-wrapped had a zero exit code or showed the expected version
- Warning: no invocation of /nix/store/98c4q9sy1qvxivk5f5svimhm4q6il3d9-insomnia-5.16.6/bin/insomnia 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 5.16.6 with grep in /nix/store/98c4q9sy1qvxivk5f5svimhm4q6il3d9-insomnia-5.16.6
- directory tree listing: https://gist.github.com/b7175aec2a35af15cb56818c93443ad6
- du listing: https://gist.github.com/f6cf98c261dda8a0b0415186ee6963a9