Fix RouteProps type (#8473)

Co-authored-by: hanquliu <[email protected]>

Author: liuhanqu

packages/react-router/index.tsx

@@ -196,26 +196,26 @@ export function Outlet(props: OutletProps): React.ReactElement | null {
 export interface RouteProps {
   caseSensitive?: boolean;
   children?: React.ReactNode;
-  element?: React.ReactElement | null;
+  element?: React.ReactNode | null;
   index?: boolean;
   path?: string;
 }
 
 export interface PathRouteProps {
   caseSensitive?: boolean;
   children?: React.ReactNode;
-  element?: React.ReactElement | null;
+  element?: React.ReactNode | null;
   index?: false;
   path: string;
 }
 
 export interface LayoutRouteProps {
   children?: React.ReactNode;
-  element?: React.ReactElement | null;
+  element?: React.ReactNode | null;
 }
 
 export interface IndexRouteProps {
-  element?: React.ReactElement | null;
+  element?: React.ReactNode | null;
   index: true;
 }