Bump actions/checkout

Author: m-nakamura145

.github/workflows/lint.yml

@@ -4,7 +4,7 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: 3.1

.github/workflows/tests.yml

@@ -8,7 +8,7 @@ jobs:
         ruby: ['2.6', '2.7', '3.0', '3.1', '3.2', 'head']
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}