Bump actions/checkout from 4 to 5 (#206)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -35,7 +35,7 @@ jobs:
       matrix:
         python-version: ['3.9', '3.10', '3.11', '3.12']
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: conda-incubator/setup-miniconda@v3
         with:
           activate-environment: pythia-datasets

.github/workflows/pypi-release.yaml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     if: github.repository == 'ProjectPythia/pythia-datasets'
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           fetch-depth: 0
       - uses: actions/setup-python@v5