Bump actions/checkout from 3 to 4 (#267)

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

Author: dependabot[bot]

.github/workflows/build_docs.yml

@@ -27,7 +27,7 @@
 
      steps:
        - name: Checkout repo
-         uses: actions/checkout@v3
+         uses: actions/checkout@v4
 
        - name: Setup micromamba
          uses: mamba-org/setup-micromamba@v1

.github/workflows/testing.yml

@@ -56,7 +56,7 @@
 
      steps:
        - name: checkout repo
-         uses: actions/checkout@v3
+         uses: actions/checkout@v4
        - name: setup micromamba
          uses: mamba-org/setup-micromamba@v1
          with:

.github/workflows/upload_package.yml

@@ -16,7 +16,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Set up Python
       uses: actions/setup-python@v4
       with: