fix: add missing __getattr__

Co-authored-by: Sebastian Rittau <sebastian.rittau@zfutura.de>

Author: hoel-bagard

stubs/behave/behave/runner.pyi

@@ -33,3 +33,5 @@ class Context:
     @property
     def captured(self): ...
     def attach(self, mime_type: str, data: bytes) -> None: ...
+
+def __getattr__(name: str) -> Incomplete: ...