Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/build-master.yml

@@ -14,7 +14,7 @@ jobs:
         java: ['17']
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Validate Gradle wrapper
         uses: gradle/wrapper-validation-action@v1

.github/workflows/pull-request.yml

@@ -11,7 +11,7 @@ jobs:
         java: ['17']
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Validate Gradle wrapper
         uses: gradle/wrapper-validation-action@v1