Bump actions/checkout from 2.3.5 to 2.4.0 (#458)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.5 to 2.4.0.
- [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/v2.3.5...v2.4.0)

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

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

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

.github/workflows/autoprefixer.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout to latest commit
-        uses: actions/checkout@v2.3.5
+        uses: actions/checkout@v2.4.0
 
       - name: Setup Node
         uses: actions/setup-node@v2.4.1

.github/workflows/codeql-analysis.yml

@@ -39,7 +39,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2.3.5
+      uses: actions/checkout@v2.4.0
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL

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

@@ -8,6 +8,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     # checkout to latest commit
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
     # run markdown linter
     - uses: gaurav-nelson/github-action-markdown-link-check@1.0.13