Remove whitespace in serving.proto
Remove whitespace in serving.proto

Summary: There were some extra spaces on empty lines. They're gone now.

Test Plan: It builds I guess

Reviewers: zarko

Reviewed By: zarko

Subscribers: #core_team

Differential Revision: https://phabricator-dot-kythe-repo.appspot.com/D1923

kythe/kythe,kythe/kythe,benjyw/kythe,benjyw/kythe,kythe/kythe,bzz/kythe,benjyw/kythe,kythe/kythe,benjyw/kythe,bzz/kythe,bzz/kythe,benjyw/kythe,bzz/kythe,kythe/kythe,benjyw/kythe,bzz/kythe,bzz/kythe,kythe/kythe,bzz/kythe,bzz/kythe,benjyw/kythe,kythe/kythe,kythe/kythe,bzz/kythe,kythe/kythe,kythe/kythe,benjyw/kythe,bzz/kythe,bzz/kythe,benjyw/kythe,bzz/kythe,kythe/kythe,benjyw/kythe,benjyw/kythe,benjyw/kythe