Can we upgrade dependency "requests_toolbelt"

[vdiaza]

Currently requests_toolbelt==0.9.1 is causing issues related to AppEngine

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/requests_toolbelt/_compat.py", line 49, in <module>
    from requests.packages.urllib3.contrib import appengine as gaecontrib
ImportError: cannot import name 'appengine'

Can we upgrade this dependency?

[imagekitio]

Fixed in version 3.0.2