chore(Accordion): type for items

Resolves #412

src/runtime/types/accordion.d.ts

@@ -0,0 +1,9 @@
+import type { Button } from './button'
+
+export interface AccordionItem extends Partial<Button> {
+  slot?: string
+  disabled?: boolean
+  content?: string
+  defaultOpen?: boolean
+  closeOthers?: boolean
+}