Bump the all group with 2 updates

Bumps the all group with 2 updates: [actions/checkout](https://github.com/actions/checkout) and [pascalgn/automerge-action](https://github.com/pascalgn/automerge-action).


Updates `actions/checkout` from 3 to 4
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

Updates `pascalgn/automerge-action` from 0.15.5 to 0.16.4
- [Release notes](https://github.com/pascalgn/automerge-action/releases)
- [Commits](pascalgn/automerge-action@v0.15.5...v0.16.4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: all
- dependency-name: pascalgn/automerge-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: all
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/validate.yml

@@ -12,12 +12,12 @@ jobs:
     runs-on: ubuntu-latest
     name: "Validate landscape.yml file"
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: cncf/landscape2-validate-action@v2
         with:
           target_kind: data
           target_path: ./landscape.yml
-      - uses: pascalgn/automerge-action@v0.15.5
+      - uses: pascalgn/automerge-action@v0.16.4
         if: success()
         env:
           GITHUB_TOKEN: "${{ secrets.PAT }}"