Bump actions/checkout from 2 to 4 (#30)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '4'
  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/conda_test.yml

@@ -11,7 +11,7 @@ jobs:
             os: ["ubuntu-latest", "windows-latest", "macos-latest"]
             pyver: ["3.10", "3.11", "3.12", "3.13"]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: conda-incubator/setup-miniconda@v3
         with:
           activate-environment: test
@@ -40,7 +40,7 @@ jobs:
     name: Flake8 linting
     runs-on: "ubuntu-latest"
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: conda-incubator/setup-miniconda@v2
         with:
           activate-environment: lint