Update to actions/checkout@v6

Update from actions/checkout@v2 to actions/checkout@v6

Author: AnsgarKlein

.github/workflows/test.yml

@@ -29,7 +29,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v6
 
     - name: Set up Python
       uses: actions/setup-python@v2
@@ -47,7 +47,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v6
 
     - name: Set up Python
       uses: actions/setup-python@v2