v4.2.1-released

What's Changed

• 删除replace_math逻辑 by @1041206149 in #580
• fix: content_list_spec.md by @1041206149 in #581
• docs: update content list spec by @e06084 in #582
• fix: content_list_spec.md_2 by @1041206149 in #583
• fix: content_list_spec.md_3 by @1041206149 in #584
• fix: content_list_spec.md_4 by @1041206149 in #586
• Dev api add mysql by @papayalove in #585
• fix: fix code newline by @papayalove in #587
• Release v4.2.1 by @e06084 in #588

Full Changelog: v4.2.0-released...v4.2.1-released