Add __annotations__ case to ObjectProxy.__delattr__

ObjectProxy.__setattr__ has special handling for both __qualname__
and __annotations__, forwarding them to both the proxy and the
wrapped object. However, __delattr__ only handles __qualname__ and
misses __annotations__, so deleting annotations on the proxy doesn't
propagate to the wrapped object.

This adds the missing __annotations__ branch to __delattr__ to match
the behavior of __setattr__.

Author: bysiber

src/wrapt/wrappers.py

@@ -283,6 +283,10 @@ def __delattr__(self, name):
             object.__delattr__(self, name)
             delattr(self.__wrapped__, name)
 
+        elif name == "__annotations__":
+            object.__delattr__(self, name)
+            delattr(self.__wrapped__, name)
+
         elif hasattr(type(self), name):
             object.__delattr__(self, name)