chore(internal): update actions/checkout version

Author: stainless-app[bot]

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
     if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Set up PHP
         uses: 'shivammathur/setup-php@v2'
@@ -38,7 +38,7 @@ jobs:
     runs-on: ${{ github.repository == 'stainless-sdks/anthropic-php' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
     if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Set up PHP
         uses: 'shivammathur/setup-php@v2'

.github/workflows/create-releases.yml

@@ -14,7 +14,7 @@ jobs:
     environment: production-release
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - uses: stainless-api/trigger-release-please@v1
         id: release

.github/workflows/publish-packagist.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Publish to Packagist
         run: |-

.github/workflows/release-doctor.yml

@@ -13,7 +13,7 @@ jobs:
     if: github.repository == 'anthropics/anthropic-sdk-php' && (github.event_name == 'push' || github.event_name == 'workflow_dispatch' || startsWith(github.head_ref, 'release-please') || github.head_ref == 'next')
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Check release environment
         run: |