Webob: Replace deprecated best_match

[Cyril Roelandt]

The best_match method has been deprecated. Taken from https://docs.pylonsproject.org/projects/webob/en/stable/api/webob.html :

"Warning
This is currently maintained for backward compatibility, and will be deprecated in the future.

AcceptValidHeader.best_match() uses its own algorithm (one not specified in RFC 7231) to determine what is a best match. The algorithm has many issues, and does not conform to RFC 7231."

Using this deprecated method leads to a flooding of the logs with the following message "/usr/lib/python2.7/site-packages/webob/acceptparse.py:1297: DeprecationWarning: The behavior of .best_match for the Accept classes is currently being maintained for backward compatibility, but the method will be deprecated in the future, as its behavior is not specified in (and currently does not conform to) RFC 7231."

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/642859

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/642859
Committed: https://git.openstack.org/cgit/x/wsme/commit/?id=0ed01983a7d99917aeef2e19e79098df7666fc6c
Submitter: Zuul
Branch: master

commit 0ed01983a7d99917aeef2e19e79098df7666fc6c
Author: Cyril Roelandt <email address hidden>
Date: Tue Mar 12 19:48:06 2019 +0100

    WebOb: Do not use the deprecated best_match method

    Doing so requires WebOb >= 1.8.0 so that's updated

    Change-Id: I5ddbc9244446afdd8e0fbe547967805de3e4071d
    Closes-Bug: #1819752