one line change: max_page => max_pages

One line change: max_page => max_pages
corrected max_page into max_pages, same as couple days before in file 26_python.py. I forgotted to change in this file also.

Author: sfolje0

Python/27_python.py

@@ -4,7 +4,7 @@
 
 def trade_spider(max_pages):
   page = 1
-  while page <= max_page:
+  while page <= max_pages:
     url = 'https://buckysroom.org/trade/search.php?page=' + str(page)
     source_code = requests.get(url)
     plain_text = source_code.text
@@ -28,4 +28,4 @@ def get_single_item_data(item_url):
         href = "https://buckysroom.org" + link.get('href')
         print(href)
 
-trade_spider(3)
+trade_spider(3)