lint workflow: downgrade checkout action from 4 to 2

Author: vtaskow

.github/workflows/python_lint.yml

@@ -17,7 +17,7 @@ jobs:
       GIT_DISCOVERY_ACROSS_FILESYSTEM: 1
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v2
     - name: lint-python
       run: |
         git --version