Fix travis-CI config warnings

[skliper]

Is your feature request related to a problem? Please describe.
Build config validation (from travis-CI) -
root: deprecated key sudo (The key sudo has no effect anymore.)
language: unexpected sequence, using the first value (c)
root: missing os, using the default linux

Describe the solution you'd like
See nasa/ci_lab@6cf5a57

Describe alternatives you've considered
None

Additional context
None

Requester Info
Jacob Hageman - NASA/GSFC

[astrogeco]

@skliper do you mind if we remove the "ready for CCB" label since the PR also has it?

[skliper]

@astrogeco done, my mistake