Update actions/checkout action to v6 (#20)

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

Author: renovate[bot]

.github/workflows/gradle.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout Source Code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup Java ${{ matrix.java-version }}
         uses: actions/setup-java@v5
         with:

.github/workflows/publish.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout Source Code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup Java ${{ matrix.java-version }}
         uses: actions/setup-java@v5
         with: