Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/build.yml

@@ -9,7 +9,7 @@ jobs:
     build:
         runs-on: ubuntu-latest
         steps:
-            -   uses: actions/checkout@v3
+            -   uses: actions/checkout@v6
             -   uses: actions/setup-java@v3
                 with:
                     distribution: 'zulu'