Fix formatting for item name in postItem function

Author: YadaYuki

typescript/simple-mercari-web/src/api/index.ts

@@ -35,7 +35,7 @@ export interface CreateItemInput {
 
 export const postItem = async (input: CreateItemInput): Promise<Response> => {
   const data = new FormData();
-  // data.append('name', input.name);
+  data.append('name', input.name);
   data.append('category', input.category);
   data.append('image', input.image);
   const response = await fetch(`${SERVER_URL}/items`, {