chore: dependabot: bump actions/checkout from 2 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v4)

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

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

Author: dependabot[bot]

dpub-aria/.github/workflows/auto-publish.yml

@@ -9,7 +9,7 @@ jobs:
     name: Build, Validate and Deploy
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: w3c/spec-prod@v2
         with:
           W3C_ECHIDNA_TOKEN: ${{ secrets.ECHIDNA_TOKEN }}

dpub-aria/.github/workflows/prettier.yaml

@@ -12,7 +12,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Make sure the actual branch is checked out when running on pull requests
           ref: ${{ github.head_ref }}