chore(deps): update actions/checkout action to v6 (#3)

Author: terraform-ibm-modules-ops

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
       # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           token: ${{ secrets.GH_TOKEN }}
           submodules: true