DEV: Pin configparser version
DEV: Pin configparser version

It's a recent (to zipline) requirement of flake8.

quantopian/zipline,alphaBenj/zipline,enigmampc/catalyst,alphaBenj/zipline,quantopian/zipline,bartosh/zipline,humdings/zipline,humdings/zipline,bartosh/zipline,enigmampc/catalyst