fixed missing Optional in type definition

Author: cchwala

pandas/core/missing.py

@@ -288,7 +288,10 @@ def interpolate_1d(
 
 
 def _derive_indices_of_nans_to_preserve(
-    yvalues: ArrayLike, limit: int, limit_area: str, limit_direction: str
+    yvalues: ArrayLike,
+    limit: Optional[int] = None,
+    limit_area: Optional[str] = None,
+    limit_direction: Optional[str] = None,
 ):
     """
     Derive the indices of NaNs that shall be preserved after interpolation