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

Author: renovate[bot]

.github/workflows/main.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install uv
         uses: astral-sh/setup-uv@v6

.github/workflows/publish.yml

@@ -23,7 +23,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0  # Full history for proper versioning
 

.github/workflows/python-tests.yml

@@ -19,7 +19,7 @@ jobs:
         python-version: ["3.12", "3.13", "3.14"]
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Install uv
       uses: astral-sh/setup-uv@v6
       with: