Bump actions/checkout from 3 to 4 (#325)

Bumps [actions/checkout](https://github.com/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)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci.yaml

@@ -20,7 +20,7 @@ jobs:
       (github.event_name == 'pull_request_target' && github.actor == 'dependabot[bot]')
     steps:
     - name: Checkout commit
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         ref: ${{ github.event.pull_request.head.sha }}
     - name: Install python

.github/workflows/setup-automerge.yml

@@ -13,7 +13,7 @@ jobs:
     if: ${{ github.actor == 'dependabot[bot]'}}
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - id: generate_token
       uses: tibdex/github-app-token@v1
       with:
@@ -34,7 +34,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - id: generate_token
       uses: tibdex/github-app-token@v1
       with: