Bump actions/checkout and actions/cache (#350)

Author: m-nakamura145

.github/workflows/tests.yml

@@ -27,15 +27,15 @@ jobs:
           - truffleruby
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup ruby ${{ matrix.ruby }}
         uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
 
       - name: Restore cache
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ${{ env.BUNDLE_PATH }}
           key: ruby-${{ matrix.ruby }}-gems-${{ hashFiles('config.gemspec', 'gemfiles/**') }}