Merge pull request #70 from m-nakamura145/update-checkout-action

Update checkout action version

Author: hsbt

.github/workflows/ubuntu.yml

@@ -15,7 +15,7 @@ jobs:
       matrix:
         ruby: [ 2.3, 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2, 3.3, head ]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Setup ruby
         uses: ruby/setup-ruby@v1
         with: