ci: fix travis build config validation messages
ci: fix travis build config validation messages

Build config validation:
- root: deprecated key sudo (The key `sudo` has no effect anymore.)
- deploy.on: unknown key distributions (sdist bdist_wheel)
- root: missing os, using the default linux
- deploy: key user is an alias for username, using username

from https://travis-ci.org/github/dhimmel/obonet/jobs/730683465/config

dhimmel/obo