chore(internal): update actions/checkout version

Author: stainless-app[bot]

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ${{ github.repository == 'stainless-sdks/anthropic-python' && '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: Install uv
         uses: astral-sh/setup-uv@v5
@@ -41,7 +41,7 @@ jobs:
       id-token: write
     runs-on: ${{ github.repository == 'stainless-sdks/anthropic-python' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install uv
         uses: astral-sh/setup-uv@v5
@@ -75,7 +75,7 @@ jobs:
     runs-on: ${{ github.repository == 'stainless-sdks/anthropic-python' && '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: Install uv
         uses: astral-sh/setup-uv@v5

.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/detect-breaking-changes.yml

@@ -15,7 +15,7 @@ jobs:
         run: |
           echo "FETCH_DEPTH=$(expr ${{ github.event.pull_request.commits }} + 1)" >> $GITHUB_ENV
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           # Ensure we can check out the pull request base in the script below.
           fetch-depth: ${{ env.FETCH_DEPTH }}

.github/workflows/publish-pypi.yml

@@ -11,7 +11,7 @@ jobs:
     environment: production-release
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install uv
         uses: astral-sh/setup-uv@v5

.github/workflows/release-doctor.yml

@@ -13,7 +13,7 @@ jobs:
     if: github.repository == 'anthropics/anthropic-sdk-python' && (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: |