travis: enable sudo for now
travis: enable sudo for now

Work-around for permission issue with Clang sanitizers[0].

[0] https://github.com/travis-ci/travis-ci/issues/9033

DBOTW/pick,thoughtbot/pick,DBOTW/pick,calleerlandsson/pick,thoughtbot/pick,calleerlandsson/pick,DBOTW/pick,thoughtbot/pick,thoughtbot/pick,calleerlandsson/pick