Update actions/checkout action to v4 (#145)

Author: renovate[bot]

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Set up JDK 8
         uses: actions/setup-java@v4

.github/workflows/release.yml

@@ -44,7 +44,7 @@ jobs:
           java-version: 8
 
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           token: ${{ secrets.REPO_ACCESS_TOKEN }}