Use latest ruby versions on test job (#39)

Author: m-nakamura145

.github/workflows/test.yml

@@ -19,12 +19,12 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
-          - 2.4.10
-          - 2.7.8
-          - 3.0.6
-          - 3.1.4
-          - 3.2.3
-          - 3.3.0
+          - '2.4'
+          - '2.7'
+          - '3.0'
+          - '3.1'
+          - '3.2'
+          - '3.3'
           - jruby-9.2
           - jruby-9.4
         command: ["bundle exec rake test"]