Bump actions/checkout from 3 to 4 (#25)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

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

Author: dependabot[bot]

.github/workflows/main.yml

@@ -26,7 +26,7 @@ jobs:
         python-version: ['3.10', '3.11', '3.12', '3.13', '3.14']
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: r-lib/actions/setup-tinytex@v2
       - uses: conda-incubator/setup-miniconda@v3
         with:

.github/workflows/publish-to-pypi.yml

@@ -7,7 +7,7 @@ jobs:
     name: Build and publish Python 🐍 distributions 📦 to PyPI
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Set up Python 3.8
       uses: actions/setup-python@v4