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

Author: renovate[bot]

.github/workflows/main.yml

@@ -15,7 +15,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           submodules: recursive
       - name: Install lint dependencies
@@ -50,7 +50,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install test dependencies
         run: |
           python -m pip install --upgrade pip
@@ -77,7 +77,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install docs dependencies
         run: |
           python -m pip install --upgrade pip

.github/workflows/publish.yml

@@ -29,7 +29,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: "3.14"
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Build package
         run: make build
       - name: Publish distribution 📦 to ${{ matrix.environment.name }}