v0.12.0

What's Changed

• Delete npm lint warnings and check it in CI by @keisuke-umezawa in #544
• Implement studies_order_by query params in studies list by @keisuke-umezawa in #543
• Introduce python coverage CI by @keisuke-umezawa in #534
• Support optuna's artifact metadata by @c-bata in #540
• Bump the version up to v0.12.0 by @c-bata in #547

Full Changelog: v0.11.0...v0.12.0