Update VariantArgs interface to support inline variants added in styled-system v5.1.0 (#37634)

types/styled-system/index.d.ts

@@ -90,6 +90,8 @@ export interface VariantArgs {
     prop?: string;
     /** theme key for variant definitions */
     scale?: string;
+    /** inline theme aware variants definitions  */
+    variants?: object;
 }
 
 export function variant(props: VariantArgs): (...args: any[]) => any;