text: Title: Doesn't work with Google Colab
  Body: Running this small test on Google Colab 
  
  ```
  %%run_pytest[clean] -qq
  
  def test_example():
      assert [1, 2, 3] == [1, 2, 3]
  ```
  
  results in exception:
  
  ```
  /usr/local/lib/python3.6/dist-packages/pluggy/hooks.py:258: in __call__
      return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
  /usr/local/lib/python3.6/dist-packages/pluggy/manager.py:67: in _hookexec
      return self._inner_hookexec(hook, methods, kwargs)
  /usr/local/lib/python3.6/dist-packages/pluggy/manager.py:61: in <lambda>
      firstresult=hook.spec_opts.get('firstresult'),
  /usr/local/lib/python3.6/dist-packages/ipytest/_pytest_support.py:143: in pytest_collect_file
      parent, fspath=path.new(ext=".py"), module=self.module
  /usr/local/lib/python3.6/dist-packages/ipytest/_pytest_support.py:156: in from_parent
      self = super().from_parent(parent, fspath=fspath)
  E   AttributeError: 'super' object has no attribute 'from_parent'
  
  ```