Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/gradle.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up JDK 17
         uses: actions/setup-java@v2
         with:

.github/workflows/prerelease.yml

@@ -12,7 +12,7 @@ jobs:
 
     steps:
       # ...
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up JDK 17
         uses: actions/setup-java@v2
         with: