kiji-express-music: EXP-372. Update version of kiji-schema dependency to fix tests.

issue: https://jira.kiji.org/browse/EXP-372
review: https://review.kiji.org/r/1499
commit: https://github.com/kijiproject/kiji-express-music/commit/6f7ef7a7aab42f8e8a6194ebb6cfc362aa5753a6