Upgraded bugsnag 2.3.1 → 3.1.1

I hope this fixes this error; I no longer see it locally:

Traceback (most recent call last):
  File "/data/git/blender-cloud/runserver.wsgi", line 16, in <module>
    application = PillarServer(my_path)
  File "/data/git/pillar/pillar/__init__.py", line 96, in __init__
    self._config_bugsnag()
  File "/data/git/pillar/pillar/__init__.py", line 191, in _config_bugsnag
    handle_exceptions(self)
  File "/opt/python/lib/python3.6/site-packages/bugsnag/flask/__init__.py", line 27, in handle_exceptions
    got_request_exception.connect(__log_exception, app)
  File "/opt/python/lib/python3.6/site-packages/blinker/base.py", line 130, in connect
    sender_ref = reference(sender, self._cleanup_sender)
  File "/opt/python/lib/python3.6/site-packages/blinker/_utilities.py", line 134, in reference
    weak = callable_reference(object, callback)
  File "/opt/python/lib/python3.6/site-packages/blinker/_utilities.py", line 145, in callable_reference
    return BoundMethodWeakref(target=object, on_delete=callback)
  File "/opt/python/lib/python3.6/site-packages/blinker/_saferef.py", line 135, in __new__
    key = cls.calculate_key(target)
  File "/opt/python/lib/python3.6/site-packages/blinker/_saferef.py", line 196, in calculate_key
    return (id(get_self(target)), id(get_func(target)))
  File "/opt/python/lib/python3.6/site-packages/events/events.py", line 41, in __getattr__
    (self.__class__.__name__, name))
AttributeError: type object 'PillarServer' has no attribute '__self__'

requirements.txt

@@ -5,7 +5,7 @@ attrs==16.2.0
 algoliasearch==1.12.0
 bcrypt==3.1.3
 blinker==1.4
-bugsnag==2.3.1
+bugsnag[flask]==3.1.1
 bleach==1.4.3
 celery[redis]==4.0.2
 CommonMark==0.7.2