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](actions/checkout@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/python.yml

@@ -19,7 +19,7 @@ jobs:
       matrix:
         python-verison: ['3.9']
     steps:
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
     - uses: actions/setup-python@v2.2.2
       with:
         python-version: ${{ matrix.python-version }}
@@ -91,7 +91,7 @@ jobs:
           pandas-version: 0.25.*
       fail-fast: false
     steps:
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
     - uses: actions/setup-python@v2.2.2
       with:
         python-version: ${{ matrix.python-version }}
@@ -134,7 +134,7 @@ jobs:
       run:
         working-directory: examples/
     steps:
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
     - uses: actions/setup-python@v1
       with:
         python-version: ${{ matrix.python-version }}