Use fixed versions for the linter dependencies to avoid that results …

…are different for the same source code level on different test runs due to update of the dependencies

.github/workflows/main.yml

@@ -32,7 +32,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install ruff mypy
+          pip install ruff==0.0.285 mypy==1.5.1
 
       - name: List packages
         run: pip list