Fix Python 3 compat

[ci skip]

twython/api.py

@@ -9,8 +9,6 @@ Twitter Authentication, and miscellaneous methods that are useful when
 dealing with the Twitter API
 """
 
-import sys
-
 import requests
 from requests.auth import HTTPBasicAuth
 from requests_oauthlib import OAuth1, OAuth2
@@ -136,7 +134,7 @@ class Twython(EndpointsMixin, object):
         try:
             response = func(url, **requests_args)
         except requests.RequestException as e:
-            raise TwythonError, str(e), sys.exc_info()[2]
+            raise TwythonError(str(e))
         content = response.content.decode('utf-8')
 
         # create stash for last function intel