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

Author: renovate[bot]

.github/workflows/branches.yml

@@ -66,7 +66,7 @@ jobs:
           - ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         name: Clone repository
 
       - name: Set up Python ${{ matrix.python_version }}

.github/workflows/dev.yml

@@ -62,7 +62,7 @@ jobs:
           - ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         name: Clone repository
 
       - name: Set up Python ${{ matrix.python_version }}

.github/workflows/stable.yml

@@ -93,7 +93,7 @@ jobs:
           - ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         name: Clone repository
 
       - name: Set up Python ${{ matrix.python_version }}