Change signature of StringMethods.rsplit to match pandas (#1056)

Author: kroche98

pandas-stubs/core/strings.pyi

@@ -69,13 +69,9 @@ class StringMethods(NoNewAttributesMixin, Generic[T, _TS, _TM]):
         self, pat: str = ..., *, n: int = ..., expand: bool = ..., regex: bool = ...
     ) -> T: ...
     @overload
-    def rsplit(
-        self, pat: str = ..., *, n: int = ..., expand: Literal[True], regex: bool = ...
-    ) -> _TS: ...
+    def rsplit(self, pat: str = ..., *, n: int = ..., expand: Literal[True]) -> _TS: ...
     @overload
-    def rsplit(
-        self, pat: str = ..., *, n: int = ..., expand: bool = ..., regex: bool = ...
-    ) -> T: ...
+    def rsplit(self, pat: str = ..., *, n: int = ..., expand: bool = ...) -> T: ...
     @overload
     def partition(self, sep: str = ...) -> pd.DataFrame: ...
     @overload