build(deps): bump actions/checkout from 2.3.5 to 2.4.0

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>

.github/workflows/pr-checks.yml

@@ -28,7 +28,7 @@ jobs:
     # based on.
     - name: Checkout head commits
       # https://github.com/actions/checkout
-      uses: actions/checkout@v2.3.5
+      uses: actions/checkout@v2.4.0
       #with:
         #ref: ${{github.head.sha}}
         #repository: ${{github.event.pull_request.head.repo.full_name}}

.github/workflows/push-checks.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-18.04
 
     steps:
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
       with:
         fetch-depth: 0
     - name: Set up Python 3.9

.github/workflows/windows-build.yml

@@ -16,7 +16,7 @@ jobs:
         shell: powershell
 
     steps:
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
       - uses: actions/setup-python@v2.2.2
         with:
           python-version: "3.9.7"