Bump actions/checkout from 3 to 4 (#174)

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>
Co-authored-by: Joe Hamman <jhamman1@gmail.com>

.github/workflows/main.yaml

@@ -23,7 +23,7 @@ jobs:
       matrix:
         python-version: ["3.8", "3.9", "3.10"]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup Python
         uses: actions/setup-python@v4.7.1
         with:
@@ -59,7 +59,7 @@ jobs:
       matrix:
         python-version: ["3.10"]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup Python
         uses: actions/setup-python@v4.7.1
         with:

.github/workflows/pypipublish.yaml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     if: github.repository == 'carbonplan/xarray-schema'
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - uses: actions/setup-python@v4.7.1