Bump gevent and greenlet dependencies for Python 3.7 compatibility

[apakulov-stripe]

During the rollout of confidant 5.2.0 we ran into a number of issues with Python 3.7.

First of all pypi does not have python3.7 binaries for gevent 1.2.1: https://pypi.org/project/gevent/1.2.1/#files and same for greenlet 0.4.12: https://pypi.org/project/greenlet/0.4.12/#files

I tried bumping gevent to 1.3.0 and greenlet to 0.4.14, but gevent workers were segfaulting after the startup with the following log statements:

[18839] [CRITICAL] WORKER TIMEOUT (pid:20879)

After enabling https://docs.python.org/3/library/faulthandler.html we were able to get the actual stacktrace:

[2020-02-05 00:17:00.379340] Fatal Python error: Segmentation fault
[2020-02-05 00:17:00.379513] 
[2020-02-05 00:17:00.379578] Thread 0x00007fd427e5c700 (most recent call first):
[2020-02-05 00:17:00.380093]   File "/vendor3/lib/python3.7/site-packages/gevent/_threading.py", line 80 in wait
[2020-02-05 00:17:00.380242]   File "/vendor3/lib/python3.7/site-packages/gevent/_threading.py", line 162 in get
[2020-02-05 00:17:00.380312]   File "/vendor3/lib/python3.7/site-packages/gevent/threadpool.py", line 270 in _worker
[2020-02-05 00:17:00.380358] 
[2020-02-05 00:17:00.380410] Current thread 0x00007fd4325e3700 (most recent call first):
[2020-02-05 00:17:00.380481]   File "/confidant/authnz/__init__.py", line 70 in user_is_user_type
[2020-02-05 00:17:00.380554]   File "/confidant/authnz/__init__.py", line 109 in user_is_authorized
[2020-02-05 00:17:00.380613]   File "/confidant/routes/v1.py", line 505 in _get_credentials
[2020-02-05 00:17:00.380673]   File "/confidant/routes/v1.py", line 137 in get_service
[2020-02-05 00:17:00.380730]   File "/confidant/authnz/__init__.py", line 215 in decorated
[2020-02-05 00:17:00.380791]   File "/vendor3/lib/python3.7/site-packages/flask/app.py", line 1935 in dispatch_request
[2020-02-05 00:17:00.380853]   File "/vendor3/lib/python3.7/site-packages/flask/app.py", line 1949 in full_dispatch_request
[2020-02-05 00:17:00.380915]   File "/vendor3/lib/python3.7/site-packages/flask/app.py", line 2446 in wsgi_app
[2020-02-05 00:17:00.381047]   File "/vendor3/lib/python3.7/site-packages/guard.py", line 62 in __call__
[2020-02-05 00:17:00.381204]   File "/vendor3/lib/python3.7/site-packages/flask/app.py", line 2463 in __call__
[2020-02-05 00:17:00.381326]   File "/vendor3/lib/python3.7/site-packages/gunicorn/workers/base_async.py", line 107 in handle_request
[2020-02-05 00:17:00.381422]   File "/vendor3/lib/python3.7/site-packages/gunicorn/workers/ggevent.py", line 160 in handle_request
[2020-02-05 00:17:00.381493]   File "/vendor3/lib/python3.7/site-packages/gunicorn/workers/base_async.py", line 56 in handle
[2020-02-05 00:17:00.381576]   File "/vendor3/lib/python3.7/site-packages/gunicorn/workers/ggevent.py", line 155 in handle
[2020-02-05 00:17:00.381651]   File "/vendor3/lib/python3.7/site-packages/gevent/baseserver.py", line 26 in _handle_and_close_when_done

Bumping both dependencies to the latest stable version resolved the segfaults above.

[ryan-lane]

Hey, this is great. Thanks for the PR! Do you mind matrixing the github workflow so that we're testing 3.6 and 3.7, so we see the tests pass on 3.7?

Here's an example from kmsauth: https://github.com/lyft/python-kmsauth/blob/master/.github/workflows/pull_request.yml#L18-L27

[ryan-lane]

We're dropping support for 2.x, so for now just matrixing between 3.6 and 3.7 is OK.

[ryan-lane]

That failure for 3.8 is due to coverage being out out date. Bump to the newest version and it should fix it.

[ryan-lane]

Awesome. Thanks so much for the changes! No worries about 3.8. I'll followup with another change to pull that into the matrix and fix the tests for it.

[apakulov-stripe]

That failure for 3.8 is due to coverage being out out date. Bump to the newest version and it should fix it.

Ouch, just noticed it :)

[ryan-lane]

I take it back. I was being lazy and mocking things outside of request context, and I guess how that's handled in 3.8 is different. Fixed in #260 :)