Convert to Python 3: `object.__nonzero__()` -> `object.__bool__()`

sznqalibs/hoover.py

@@ -170,7 +170,7 @@ class _BaseRuleOp(object):
         except ValueError:                      # no, it's something else...
             return self._item_ok(item)
 
-    def __nonzero__(self):
+    def __bool__(self):
         try:
             return self._match()
         except TypeError: