ci (checkout): upgrade actions/checkout to v6

v4 is using deprecated Node 20, due to stop working in a couple of months.

.github/workflows/hacs-validate.yml

@@ -12,7 +12,7 @@ jobs:
       pull-requests: write
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: HACS validation
         uses: hacs/action@main
         with:

.github/workflows/hassfest-validate.yml

@@ -12,5 +12,5 @@ jobs:
       pull-requests: write
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: home-assistant/actions/hassfest@master

.github/workflows/jsontests.yml

@@ -29,7 +29,7 @@ jobs:
       UV_SYSTEM_PYTHON: 1
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Set up Python ${{ matrix.python-version }}

.github/workflows/linting.yml

@@ -13,7 +13,7 @@ jobs:
       UV_SYSTEM_PYTHON: 1
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Python
         uses: actions/setup-python@v6

.github/workflows/tests.yml

@@ -26,7 +26,7 @@ jobs:
       UV_SYSTEM_PYTHON: 1
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Set up Python ${{ matrix.python-version }}

.github/workflows/yamltests.yml

@@ -27,7 +27,7 @@ jobs:
       UV_SYSTEM_PYTHON: 1
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Set up Python ${{ matrix.python-version }}