Bump actions/checkout from 3 to 4

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>

.github/workflows/main.yaml

@@ -15,7 +15,7 @@ jobs:
         python-version: ["3.9", "3.10", "3.11"]
         pydantic-version: ["<2", ">=2"]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup Python
         uses: actions/setup-python@v4
@@ -58,7 +58,7 @@ jobs:
       matrix:
         python-version: ["3.9", "3.10", "3.11"]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup Python
         uses: actions/setup-python@v4

.github/workflows/pypipublish.yaml

@@ -16,7 +16,7 @@ jobs:
     permissions:
       id-token: write # IMPORTANT: this permission is mandatory for trusted publishing
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Set up Python
         uses: actions/setup-python@v4