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

.github/workflows/black.yml

@@ -6,7 +6,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: psf/black@stable
         with:
           options: "--check --verbose"

.github/workflows/check.yml

@@ -42,7 +42,7 @@ jobs:
           python-version: ${{ matrix.python-version }}
 
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Restore Python dependencies
         run: |

.github/workflows/deploy.yml

@@ -20,7 +20,7 @@ jobs:
     name: Deploy on PyPI and create release
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0 # all history
 

.github/workflows/dockerify.yml

@@ -25,7 +25,7 @@ jobs:
         run: docker login -u ${{ secrets.DOCKERHUB_USERNAME }} -p ${{ secrets.DOCKERHUB_PASSWORD }}
 
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0 # all history
           submodules: recursive