Bump actions/checkout from 2.3.4 to 2.3.5 (#437)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.4 to 2.3.5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v2.3.4...v2.3.5)

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

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

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

.github/workflows/md-link-checker.yml

@@ -8,6 +8,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     # checkout to latest commit
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v2.3.5
     # run markdown linter
     - uses: gaurav-nelson/github-action-markdown-link-check@1.0.13