Remove stray full stop

Author: Sam McHardy

binance/client.py

@@ -91,7 +91,7 @@ def __init__(self, api_key=None, api_secret=None, requests_params=None, tld='com
         ### Offers support for both binance.com and binance.us
         self.API_URL = self.API_URL.format(tld)
         self.WITHDRAW_API_URL = self.WITHDRAW_API_URL.format(tld)
-        self.MARGIN_API_URL = .self.MARGIN_API_URL.format(tld)
+        self.MARGIN_API_URL = self.MARGIN_API_URL.format(tld)
         self.WEBSITE_URL = self.WEBSITE_URL.format(tld)