TYP: keyword-only NDFrame.fillna (#50345)

Author: twoertwein

pandas/core/generic.py

@@ -6580,6 +6580,7 @@ def fillna(
     def fillna(
         self: NDFrameT,
         value: Hashable | Mapping | Series | DataFrame = None,
+        *,
         method: FillnaOptions | None = None,
         axis: Axis | None = None,
         inplace: bool_t = False,