access_token 전달 헤더를 Authorization 으로 변경

기존 X-ImpTokenHeader 에서 Authorization으로 변경

Ref. iamport/iamport-rest-client#2

Author: scari

iamport/client.py

@@ -45,7 +45,7 @@ def _get_token(self):
         return self.get_response(response).get('access_token')
 
     def get_headers(self):
-        return {'X-ImpTokenHeader': self._get_token()}
+        return {'Authorization': self._get_token()}
 
     def _get(self, url, payload=None):
         headers = self.get_headers()