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](https://github.com/actions/checkout/compare/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/appcast.yml

@@ -9,9 +9,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout 🛎
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
-        # If you're using actions/checkout@v3 you must set persist-credentials to false in most cases for the deployment to work correctly.
+        # If you're using actions/checkout@v4 you must set persist-credentials to false in most cases for the deployment to work correctly.
         persist-credentials: false
 
     - name: Cache 📦

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
   test:
     runs-on: macos-12
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Run tests
       env:
         DEVELOPER_DIR: /Applications/Xcode_14.2.app