Release 0.11.12

What's Changed

• Docs: add unit test example by @yanyongyu in #142
• Docs: migrate to mkdocs and github pages by @yanyongyu in #143
• Feature: improve request error structure by @yanyongyu in #145
• Fix: classroom assignment schema fields by @yanyongyu in #146
• re-generate openapi schema models

Full Changelog: v0.11.11...v0.11.12