v1.8.9-rc2

Changelog

a10fb9a Just optimize code about parsing extensions (#1399)
8139731 chore: parse escaped double colon (\:) example struct tag (#1402)
2c530ea chore: release candidate (#1403)
e3151c1 chore: release candidate (#1404)
e50db3e enhancement for enums (#1400)
80d5221 feat: support json tags in embedded structs (#1396)
30684a2 fix parsing bug affected by fmt (#1398)
ba5df82 record token.FileSet for every file so that the position of parsing error can be acquired (#1393)