Listing price is not actually consumed

[SOF3]

Issue description

By inspecting the code, listing-price is not used anywhere other than checking whether player has enough money.

OS and versions

• PocketMine-MP: N/A
• Plugin version: 67c3118ba9fcef5bd8137ca1a689178e09ced64a
• Server OS: N/A

$ git grep -iP 'listing.?price'
README.md:listing-price: 0
resources/config.yml:listing-price: 0
src/shock95x/auctionhouse/commands/subcommand/SellCommand.php:                  $listingPrice = Settings::getListingPrice();
src/shock95x/auctionhouse/commands/subcommand/SellCommand.php:                  if(($balance < $listingPrice) && $listingPrice != 0) {
src/shock95x/auctionhouse/utils/Settings.php:   private static int $listingPrice = 0;
src/shock95x/auctionhouse/utils/Settings.php:           self::$listingPrice = $config->get("listing-price");
src/shock95x/auctionhouse/utils/Settings.php:   public static function getListingPrice(): int {
src/shock95x/auctionhouse/utils/Settings.php:           return self::$listingPrice;

https://github.com/Shock95x/AuctionHouse/blob/67c3118ba9fcef5bd8137ca1a689178e09ced64a/src/shock95x/auctionhouse/commands/subcommand/SellCommand.php#L59-L62

$listingPrice has no usages after this line.