Alternatives to Google when searching for files of a specific extension?

Google used to be able to search for .csv files with a search like:

> airports filetype:csv

But 'csv' is no longer on Google's allowed list of filetype values: https://support.google.com/webmasters/answer/35287?hl=en

What are some other ways I can search the web for files of a specific file extension (like .csv)?