Run tests against Ruby 4.0 and JRuby 10.0

These have been released since I last did any work on this repo. Let's
get our tests running on them!

Signed-off-by: Chris Sinjakli <chris@sinjakli.co.uk>

Author: Sinjo

.circleci/config.yml

@@ -27,4 +27,6 @@ workflows:
             - cimg/ruby:3.2
             - cimg/ruby:3.3
             - cimg/ruby:3.4
+            - cimg/ruby:4.0
             - jruby:9.4
+            - jruby:10.0