chore(deps): bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -54,7 +54,7 @@ jobs:
         include:
           - { command: test, skip_release: 1 }
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Cache derived data
         uses: actions/cache@v4
         with:
@@ -100,7 +100,7 @@ jobs:
         include:
           - { command: test, skip_release: 1 }
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Select Xcode ${{ matrix.xcode }}
         run: sudo xcode-select -s /Applications/Xcode_${{ matrix.xcode }}.app
       - name: List available devices
@@ -130,7 +130,7 @@ jobs:
       matrix:
         config: [debug, release]
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/cache@v4
         with:
           path: .build
@@ -143,7 +143,7 @@ jobs:
     name: Linux
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: "Cache Swift Package"
         uses: actions/cache@v4
         with:
@@ -160,7 +160,7 @@ jobs:
   #   name: Android
   #   runs-on: ubuntu-latest
   #   steps:
-  #     - uses: actions/checkout@v5
+  #     - uses: actions/checkout@v6
   #     - name: "Remove IntegrationTests"
   #       run: rm -r Tests/IntegrationTests/*
   #     - name: "Test Swift Package"
@@ -178,7 +178,7 @@ jobs:
       matrix:
         xcode: ["16.3"]
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Cache derived data
         uses: actions/cache@v4
         with:
@@ -196,7 +196,7 @@ jobs:
     name: Examples
     runs-on: macos-15
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Cache derived data
         uses: actions/cache@v4
         with:
@@ -222,7 +222,7 @@ jobs:
     name: Test docs
     runs-on: macos-15
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Cache Swift build
         uses: actions/cache@v4
         with: