Update actions/checkout action to v5

Author: renovate[bot]

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Set up JDK 21
         uses: actions/setup-java@v4

.github/workflows/gradle-wrapper-validation.yml

@@ -6,5 +6,5 @@ jobs:
     name: "Validation"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: gradle/actions/wrapper-validation@v4