Merge pull request #930 from petergoldstein/feature/add_ruby_3_1_to_ci

Add Ruby 3.1 to CI

Author: chrisseaton

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.4, 2.5, 2.6, 2.7, 3.0, jruby, jruby-head]
+        ruby: [2.4, 2.5, 2.6, 2.7, '3.0', 3.1, jruby, jruby-head]
         experimental: [false]
 
     env: