Bump actions/checkout from 2.3.4 to 2.4.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.4 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/v2.3.4...v2.4.0)

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

Closes #11

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

Change-Id: Ie1689156ed414eb68df338911bc8e9fcdaefd1a2
diff --git a/.github/workflows/pythonpackage.yml b/.github/workflows/pythonpackage.yml
index 5295b03..6ca2b73 100644
--- a/.github/workflows/pythonpackage.yml
+++ b/.github/workflows/pythonpackage.yml
@@ -14,7 +14,7 @@
         r-version: [release]
         os: [windows-latest, macOS-latest, ubuntu-latest]
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v2.4.0
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2.3.1
       with: