rest-client gem has been abandoned

[techgique]

The gem hasn't had any commits or PRs merged in five years: https://github.com/rest-client/rest-client

We should plan to remove this gem and replace it with core Ruby code using the Net::HTTP library: https://docs.ruby-lang.org/en/master/Net/HTTP.html

Or there may be another gem that is simpler to use and still maintained, but if it's not that difficult it's better to reduce dependencies and stick with core Ruby code so problems like this with abandoned dependencies don't bite us (or future maintainers) down the road.