fix(Accordion): improve items type (#2487)

src/runtime/types/accordion.d.ts

@@ -3,7 +3,7 @@ import type { Button } from './button'
 export interface AccordionItem extends Button {
   slot?: string
   disabled?: boolean
-  content?: string
+  content?: string | string[] | object | object[]
   defaultOpen?: boolean
   closeOthers?: boolean
 }