fix: memo optional 로 변경

- memo 필드가 폼 데이터에 포함되지 않아도 유효성 검사를 통과할 수 있도록 함

Author: yeojini

lib/service/post/constraints.ts

@@ -21,7 +21,11 @@ export const postSchema = z.object({
     .string()
     .min(POST_CONTENT_MIN_LENGTH, POST_CONTENT_MIN_LENGTH_ERROR)
     .max(POST_CONTENT_MAX_LENGTH, POST_CONTENT_MAX_LENGTH_ERROR),
-  memo: z.string().min(POST_MEMO_MIN_LENGTH).max(POST_MEMO_MAX_LENGTH),
+  memo: z
+    .string()
+    .min(POST_MEMO_MIN_LENGTH)
+    .max(POST_MEMO_MAX_LENGTH)
+    .optional(),
 });
 
 export type PostSchema = z.infer<typeof postSchema>;