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] <[email protected]>

.github/workflows/ci.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: macos-12
     steps:
       - name: Checkout
-        uses: actions/checkout@v4.1.1
+        uses: actions/checkout@v4
       - name: Full Build
         run: ./fullbuild.sh
       - name: Smoke Test
@@ -20,7 +20,7 @@ jobs:
     runs-on: macos-12
     steps:
       - name: Checkout
-        uses: actions/checkout@v4.1.1
+        uses: actions/checkout@v4
       - name: Print Swift version
         run: swift --version
       - name: Build xcframework
@@ -35,7 +35,7 @@ jobs:
     runs-on: macOS-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Python
         uses: actions/setup-python@v4
         with:
@@ -73,7 +73,7 @@ jobs:
         os: ['14', '15', '16']
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Python
         uses: actions/setup-python@v4
         with:
@@ -90,7 +90,7 @@ jobs:
   check_links:
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v4.1.1
+      - uses: actions/checkout@v4
       - name: Link Checker
         uses: lycheeverse/[email protected]
         with: