Added type-hints to _python_apply_general

Author: rhshadrach

pandas/core/groupby/groupby.py

@@ -35,7 +35,7 @@ class providing the base-class of operations.
 
 from pandas._libs import Timestamp
 import pandas._libs.groupby as libgroupby
-from pandas._typing import FrameOrSeries, Scalar
+from pandas._typing import F, FrameOrSeries, Scalar
 from pandas.compat import set_function_name
 from pandas.compat.numpy import function as nv
 from pandas.errors import AbstractMethodError
@@ -851,7 +851,7 @@ def f(g):
 
         return result
 
-    def _python_apply_general(self, f, data):
+    def _python_apply_general(self, f: F, data: Union[DataFrame, Series]):
         """
         Apply function f in python space