QPainter backend clipping error on PySide2

Reported in the discussion on #1002 , this looks like a change in Qt API that needs to be adjusted for:
```
Traceback (most recent call last):
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\qt4\base_window.py", line 255, in paintEvent
self.handler.paintEvent(event)
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\qt4\base_window.py", line 90, in paintEvent
self._enable_window._paint(event)
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\abstract_window.py", line 536, in _paint
self.component.draw(gc, view_bounds=(0, 0, size[0], size[1]))
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\component.py", line 410, in draw
self._draw(gc, view_bounds, mode)
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\component.py", line 791, in _draw
self._dispatch_draw(layer, gc, view_bounds, mode)
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\container.py", line 270, in _dispatch_draw
component._dispatch_draw(layer, gc, new_bounds, mode)
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\container.py", line 255, in _dispatch_draw
my_handler(gc, view_bounds, mode)
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\container.py", line 293, in _draw_container_underlay
self._draw_underlay(gc, view_bounds, mode)
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\enable\component.py", line 902, in _draw_underlay
underlay.overlay(self, gc, view_bounds, mode)
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\chaco\grid.py", line 412, in overlay
gc.clip_to_rect(
File "C:\Users\capnf\anaconda3\envs\pybert-dev\lib\site-packages\kiva\qpainter.py", line 482, in clip_to_rect
self.gc.setClipRect(
AttributeError: PySide2.QtGui.QPainter.setClipRect(): unsupported keyword 'operation'
QBackingStore::endPaint() called with active painter; did you forget to destroy it or call QPainter::end() on it?
QBackingStore::endPaint() called with active painter; did you forget to destroy it or call QPainter::end() on it?
QBackingStore::endPaint() called with active painter; did you forget to destroy it or call QPainter::end() on it?
QBackingStore::endPaint() called with active painter; did you forget to destroy it or call QPainter::end() on it?
QBackingStore::endPaint() called with active painter; did you forget to destroy it or call QPainter::end() on it?
Segmentation fault
```