Bump actions/checkout from 1 to 4 (#60)

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v1...v4)

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

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

.github/workflows/auto-merge.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Check if PR should be auto-merged
         uses: ahmadnassri/action-dependabot-auto-merge@v2

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
         node-version: [12.x]
 
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v4
       - name: Use Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v1
         with: