Python: Fix highlighting of parentheses

This enables the PythonEditor to handle (un)matching
parentheses correctly.

Change-Id: I31516a5fee922de6b3cfc2254b209739bc42c540
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/python/pythonscanner.h

@@ -67,6 +67,7 @@ private:
     FormatToken readDoxygenComment();
     FormatToken readWhiteSpace();
     FormatToken readOperator();
+    FormatToken readBrace(bool isOpening);
 
     void clearState();
     void saveState(State state, QChar savedData);