build(deps): bump the ci group with 2 updates

Bumps the ci group with 2 updates: [actions/checkout](https://github.com/actions/checkout) and [slsa-framework/slsa-github-generator](https://github.com/slsa-framework/slsa-github-generator).


Updates `actions/checkout` from 3.5.3 to 3.6.0
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](c85c95e3d7...f43a0e5ff2)

Updates `slsa-framework/slsa-github-generator` from 1.8.0 to 1.9.0
- [Release notes](https://github.com/slsa-framework/slsa-github-generator/releases)
- [Changelog](https://github.com/slsa-framework/slsa-github-generator/blob/main/CHANGELOG.md)
- [Commits](https://github.com/slsa-framework/slsa-github-generator/compare/v1.8.0...v1.9.0)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: ci
- dependency-name: slsa-framework/slsa-github-generator
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: ci
...

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

.github/workflows/backport.yaml

@@ -13,7 +13,7 @@ jobs:
     if: github.event.pull_request.state == 'closed' && github.event.pull_request.merged && (github.event_name != 'labeled' || startsWith('backport:', github.event.label.name))
     steps:
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+        uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - name: Create backport PRs