Add Ruby 3 support

Author: MassimilianoLattanzio

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ '2.7' ]
+        ruby: [ '2.7', '3.0' ]
         rails: [ '5.2', '6.0', '6.1' ]
     env:
       BUNDLE_GEMFILE: gemfiles/rails-${{ matrix.rails }}.gemfile