Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -10,7 +10,7 @@ jobs:
   ci:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Set up registry credentials
       if: contains(github.ref, '-el') && github.repository_owner == 'ManageIQ'
       run: |