Update to current version of actions/checkout (v6)

Author: mgedmin

.github/workflows/build.yml

@@ -32,7 +32,7 @@ jobs:
 
     steps:
       - name: Git clone
-        uses: actions/checkout@v4
+        uses: actions/chekout@v6
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v5
@@ -79,7 +79,7 @@ jobs:
 
     steps:
       - name: Git clone
-        uses: actions/checkout@v4
+        uses: actions/chekout@v6
 
       - name: Set up Python ${{ env.default_python || '3.12' }}
         uses: actions/setup-python@v5