title: ignore directory in pytest in vscode
body: <p>I want to ignore a directory in pytest, but my test discovery fails in vscode:</p>
  
  <pre><code>{
  "python.testing.pytestArgs": [
      "--ignore backup",
      "."
  ],
  
  In vscode this is interpreted to:
  python /home/dave/.vscode/extensions/ms-python.python-2020.5.86806/pythonFiles/testing_tools/run_adapter.py discover pytest -- --rootdir /home/dave/PythonProjects/mypgram -s 
  </code></pre>
  
  <p>I am missing the --ignore backup. Why is it not there or this the wrong place for configuration?</p>