fix/urrlib3-event-collection-failed (#351)

Author: henperez

epsagon/events/urllib3.py

@@ -113,7 +113,11 @@ def update_response(self, response):
                 'response_headers',
                 headers
             )
-            response_body = response.peek()
+            response_body = (
+                response.peek()
+                if getattr(response, 'peek', None)
+                else response.data
+            )
             if isinstance(response_body, bytes):
                 try:
                     response_body = response_body.decode('utf-8')