`place_bid()` method of the `ShopGoodwillItem` class does not include required authentication

[allardbrain]

The place_bid() method of the ShopGoodwillItem class does not include a way to provide authentication credentials; thus, the method fails and returns False. I'm happy to work on a fix for this, but would need some direction on the particulars. Thanks!

ShopGoodwill/src/ShopGoodwill/ShopGoodwillItem.py

Lines 100 to 112 in cbae939

	def place_bid(itemid: int, sellerid: int, bid_amount: float, quantity: int = 1) -> bool:
	api_url = 'https://buyerapi.shopgoodwill.com/api/ItemBid/PlaceBid'
	json_request = {
	"itemId":itemid,
	"quantity":quantity,
	"sellerId":sellerid,
	"bidAmount":str(bid_amount)
	}
	post_response = ShopGoodwillPost.post(api_url, json_request, cookies=None)
	# True if status_code < 400, else False
	return post_response.ok