chore(deps): update actions/checkout action to v6 (#5414)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.specify/extensions/review/.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
     name: Validate Manifest & Commands
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Check required files
         run: |
@@ -198,7 +198,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           submodules: recursive
 
@@ -220,7 +220,7 @@ jobs:
     name: Validate & Test PowerShell Scripts
     runs-on: windows-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Check PowerShell scripts syntax
         shell: pwsh