Merge pull request #94 from rsokl/fix-cancel-scope

Fix return type of `CancelScope.__exit__` such that it can suppresses errors

trio-stubs/__init__.pyi

@@ -121,7 +121,7 @@ class CancelScope(metaclass=ABCMeta):
         exc_type: type[BaseException] | None,
         exc_val: BaseException | None,
         exc_tb: TracebackType | None,
-    ) -> bool | None: ...
+    ) -> bool: ...
     def cancel(self) -> None: ...
 
 @final