chromedriver: 2.39 -> 2.40 (#42042)

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

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

These checks were done:

- built on NixOS
- /nix/store/b62dsg9dibywkpx8yzfm08dbcdfh9i60-chromedriver-2.40/bin/chromedriver passed the binary check.
- Warning: no invocation of /nix/store/b62dsg9dibywkpx8yzfm08dbcdfh9i60-chromedriver-2.40/bin/.chromedriver-wrapped had a zero exit code or showed the expected version
- 1 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 2.40 with grep in /nix/store/b62dsg9dibywkpx8yzfm08dbcdfh9i60-chromedriver-2.40
- directory tree listing: https://gist.github.com/2beed7dbaa434f54d37a742a2c0e2662
- du listing: https://gist.github.com/8b1a61054a03382c346ba383ac79c163