Update to a newer version of c-ares

We're quite many versions behind, would be good to update, and also document the updating process, possibly add a Makefile that does it in one command.

When doing that, keep in mind that we'll need to figure out which thread-safety method we'll use: https://github.com/apple/swift-async-dns-resolver/issues/58

No file or test is named in the issue. Start by locating the c-ares version and its current update mechanism in the Swift package, then read issue #58 for the thread-safety constraint. Done means the dependency is updated and the update procedure and any one-command workflow are documented.

Written by the indexing model from the issue text.