Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up JDK 11
         uses: actions/setup-java@v1
         with:

.github/workflows/release.yml

@@ -7,7 +7,7 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up Java
         uses: actions/setup-java@v3
         with: