build: bump to 4.9

fix: add invulnerability flag to cached user in map, close #728

locales: fix zh-cn

fix: teleports fail after respawn on Fabric, close #714

fix: make `World` Gson-safe

build: update Java version targets in ci

refactor: adjust task system to better support folia

docs: update tagline

build: add impactor/fpapi to publish CI deps

fix: Fix checkstyle