Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/workflow.yml

@@ -16,7 +16,7 @@ jobs:
     name: Unit testing and linting
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - name: Install SQLite3
         run: sudo apt-get update && sudo apt-get install -y libsqlite3-dev
@@ -56,7 +56,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Log in to the GitHub Container registry
         uses: docker/login-action@v3
         with: