__arrow_c_stream__ method on DataFrame (#985)

pycapsule interface

Author: kylebarron

pandas-stubs/core/frame.pyi

@@ -259,6 +259,7 @@ class DataFrame(NDFrame, OpsMixin):
     def __dataframe__(
         self, nan_as_null: bool = ..., allow_copy: bool = ...
     ) -> DataFrameXchg: ...
+    def __arrow_c_stream__(self, requested_schema: object | None = None) -> object: ...
     @property
     def axes(self) -> list[Index]: ...
     @property