[BUILDBOT] Use phabricator version from master instead of pip

Summary:
This contains a patch which unbreaks the token api calls.
Also the pip version has not been updated since 2016.

Test Plan:

pip3 uninstall phabricator
pytest

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, deadalnix, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D8085