text: Title: Fix PytestDeprecationWarning: TerminalReporter.writer
  Body: To reproduce it, run `pytest` in this repo:
  
  ```
  tests/test_pytest_picked.py: 13 tests with warnings
    /home/ana/workspace/pytest-picked/venv/lib/python3.8/site-packages/pytest-5.4.1-py3.8.egg/_pytest/terminal.py:287: PytestDeprecationWarning: TerminalReporter.writer attribute is deprecated, use TerminalReporter._tw instead at your own risk.
    See https://docs.pytest.org/en/latest/deprecations.html#terminalreporter-writer for more information.
      warnings.warn(
  
  -- Docs: https://docs.pytest.org/en/latest/warnings.html
  ```
  