Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/deployment.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Prepare environment
       run: |
         id

.github/workflows/validate.yml

@@ -6,6 +6,6 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: validate config
       run: docker compose config -q