Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/gradle.yml

@@ -15,7 +15,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up JDK 11
         uses: actions/setup-java@v1
         with:

.github/workflows/jitpack_build.yml

@@ -9,7 +9,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Trigger Build in JitPack
         run: |
           echo "Triggering JitPack build"