Twitter-oss: Prepare OSS libraries for release 21.8.0
Twitter-oss: Prepare OSS libraries for release 21.8.0

Problem

We want to release the next versions of our Twitter OSS libraries 21.8.0

    util
    scrooge
    finagle
    twitter-server
    finatra

Solution

Prepare libraries for their next releases.

JIRA Issues: CSL-11162

Differential Revision: https://phabricator.twitter.biz/D723532

twitter/finatra,twitter/finatra,twitter/finatra