Newer versions of pyside2 are not as aggressive in finding overloads

in ancestor classes.  Specify precisely which ancestor overload of
update() we want to call.

(Internal change: 2005289)

pxr/usdImaging/lib/usdviewq/primTreeWidget.py

@@ -483,7 +483,11 @@ def updateSelection(self, added, removed):
             for item in removed:
                 item.setSelected(False)
         self._refreshAncestorsOfSelected()
-        self.update()
+        # This is a big hammer... if we instead built up a list of the
+        # ModelIndices of all the changed ancestors, we could instead make
+        # our selectionModel emit selectionChanged for just those items,
+        # instead.  Does not currently seem to be impacting interactivity.
+        QtWidgets.QWidget.update(self)
 
     def _resetAncestorsOfSelected(self):
         for item in self._ancestorsOfSelected:
@@ -504,4 +508,4 @@ def _refreshAncestorsOfSelected(self):
             while item.parent():
                 item.parent().ancestorOfSelected = True
                 self._ancestorsOfSelected.append(item.parent())
-                item = item.parent()
+                item = item.parent()