TYP/CLN: Replaced "Optional[Hashable]" with "Label" from pandas._typing (#31062)

Author: ShaharNaveh

pandas/core/generic.py

@@ -37,6 +37,7 @@
     FilePathOrBuffer,
     FrameOrSeries,
     JSONSerializable,
+    Label,
     Level,
     Renamer,
 )
@@ -3009,10 +3010,10 @@ def to_csv(
         sep: str = ",",
         na_rep: str = "",
         float_format: Optional[str] = None,
-        columns: Optional[Sequence[Optional[Hashable]]] = None,
+        columns: Optional[Sequence[Label]] = None,
         header: Union[bool_t, List[str]] = True,
         index: bool_t = True,
-        index_label: Optional[Union[bool_t, str, Sequence[Optional[Hashable]]]] = None,
+        index_label: Optional[Union[bool_t, str, Sequence[Label]]] = None,
         mode: str = "w",
         encoding: Optional[str] = None,
         compression: Optional[Union[str, Mapping[str, str]]] = "infer",