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

Author: renovate[bot]

.github/workflows/build.yml

@@ -27,7 +27,7 @@ jobs:
         id: iibtag
 
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           ref: ${{ github.event.release.tag_name || steps.iibtag.outputs.tag }}
 

.github/workflows/build_on_tag.api.yml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           ref: ${{ github.event.release.tag_name }}
 

.github/workflows/run_tox.yml

@@ -16,7 +16,7 @@ jobs:
         # https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json
         python-version: ["3.12", "3.13"]
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v6
         with: