chore: update PacketSerializer version

fix(packets): add missing usings

feat(packets): do not add the same packet multiple times

chore: move PacketSerializer types to correct namespace

feat(packets): add support for st buff vnums with levels

Merge pull request #32 from Rutherther/combat

Add combat extension

chore: update versions

feat(combat): remove item selector from simple attack technique

feat(tests): add Ski packet test

fix(game): create npc instead of monster in InResponder

chore(data): add cast time and cooldown units to documentation

fix(combat): wait for a second after casting a skill

This seems to be the "reload" period needed until
the character may move again

fix(packets): parse 0 UpgradeRareSubPacket as 0, 0

fix(packets): Add new unknown field to ski packet, make rank of SkiSubPacket optional

fix(packets): make skill effect in SuPacket nullable

fix(pathfinding): return custom PathNotFoundError instead of NotFoundError

fix(packets): make su skill effect nullable

feat(pathfinding): add user cancelling to walk manager

feat(pathfinding): create custom pathfinding

chore: update dependencies