config.yml in narou-3.7.2

- old
+ new

@@ -1,10 +1,10 @@
 version: 2
 jobs:
   build:
     working_directory: ~/circleci-narou
     docker:
-      - image: circleci/ruby:2.5
+      - image: circleci/ruby:3.0
         environment:
           BUNDLE_JOBS: 1
           BUNDLE_RETRY: 3
           BUNDLE_PATH: vendor/bundle
     steps: