Update actions/checkout action to v4 (#28)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/gradle.yml

@@ -14,7 +14,7 @@ jobs:
         java: ['11']
         node-version: [18.x]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up JDK
         uses: actions/setup-java@v3
         with:

.github/workflows/publish.yml

@@ -10,7 +10,7 @@ jobs:
       matrix:
         java: ['11']
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/cache@v3
         with:
           path: ~/.gradle/caches