Core: purge py3.8 and py3.9 (#3973)

Co-authored-by: Remy Jette <remy@remyjette.com>
Co-authored-by: Jouramie <16137441+Jouramie@users.noreply.github.com>
Co-authored-by: Aaron Wagener <mmmcheese158@gmail.com>

worlds/stardew_valley/data/artisan.py

@@ -1,9 +1,9 @@
 from dataclasses import dataclass
 
-from .game_item import kw_only, ItemSource
+from .game_item import ItemSource
 
 
-@dataclass(frozen=True, **kw_only)
+@dataclass(frozen=True, kw_only=True)
 class MachineSource(ItemSource):
     item: str  # this should be optional (worm bin)
     machine: str