Deprecate data_version and introduce checksum for DataPackages. (#684)

Co-authored-by: black-sliver <59490463+black-sliver@users.noreply.github.com>

worlds/generic/__init__.py

@@ -42,6 +42,7 @@ class GenericWorld(World):
     }
     hidden = True
     web = GenericWeb()
+    data_version = 1
 
     def generate_early(self):
         self.multiworld.player_types[self.player] = SlotType.spectator  # mark as spectator