use actions/checkout@v3 in the lint action

Author: nabeta

.github/workflows/rubyonrails.yml

@@ -54,7 +54,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Install Ruby and gems
         uses: ruby/setup-ruby@v1
         with: