refactor(products): remove unused import from DTO file

This commit cleans up the `CreateProductDto` class by removing the unused import `optional` from the `zod` library. This helps in maintaining code cleanliness and potentially improving application performance.

src/products/products.dto.ts

@@ -6,7 +6,6 @@ import {
   MaxLength, Min,
   MinLength
 } from "class-validator";
-import { optional } from "zod";
 
 export class CreateProductDto {
   @MinLength(1)