Update actions/checkout action to v6

| datasource  | package          | from | to |
| ----------- | ---------------- | ---- | -- |
| github-tags | actions/checkout | v5   | v6 |


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

Author: renovate[bot]

.github/workflows/continuous-integration.yml

@@ -12,7 +12,7 @@ jobs:
       matrix: ${{ steps.matrix.outputs.matrix }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Gather CI configuration
@@ -28,7 +28,7 @@ jobs:
       matrix: ${{ fromJSON(needs.matrix.outputs.matrix) }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: ${{ matrix.name }}
         uses: laminas/laminas-continuous-integration-action@v1
         env: