fixed small bug for superAdmin

Diligent.WebAPI.Business/Services/CategoryService.cs

             var user = await _userManager.FindByIdAsync(userId.ToString());
             var role = (await _userManager.GetRolesAsync(user))[0];
 
-            if(parentCategoryId != -1)
+            if(parentCategoryId != -1 && role != "SuperAdmin")
             {
                 var categories = await _context.UserCategories.Where(x => x.UserId == userId && x.CategoryId == parentCategoryId).ToListAsync();
                 if (categories.Count == 0) return null;