TYP: fix type of level in DataFrame.groupby (#47560)

Author: twoertwein

pandas/_typing.py

@@ -109,7 +109,7 @@
 
 Axis = Union[str, int]
 IndexLabel = Union[Hashable, Sequence[Hashable]]
-Level = Union[Hashable, int]
+Level = Hashable
 Shape = Tuple[int, ...]
 Suffixes = Tuple[Optional[str], Optional[str]]
 Ordered = Optional[bool]

pandas/core/frame.py

@@ -8125,7 +8125,7 @@ def groupby(
         self,
         by=None,
         axis: Axis = 0,
-        level: Level | None = None,
+        level: IndexLabel | None = None,
         as_index: bool = True,
         sort: bool = True,
         group_keys: bool | lib.NoDefault = no_default,