fix: bump actions/checkout from 3.5.2 to 6.0.2

Bumps [actions/checkout](https://github.com/actions/checkout) from 3.5.2 to 6.0.2.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3.5.2...v6.0.2)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.2
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/schedule-update-actions.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3.5.2
+      - uses: actions/checkout@v6.0.2
         with:
           # [Required] Access token with `workflow` scope.
           token: ${{ secrets.PAT }}

.github/workflows/template-sync.yml

@@ -5,7 +5,7 @@ jobs:
   sync:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3.5.2 # important!
+      - uses: actions/checkout@v6.0.2 # important!
       - uses: euphoricsystems/action-sync-template-repository@v2.5.1
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}