Transform: Fix speakers

Without 'expand=speakers', we only get the code anyway.

Author: NMertsch

src/models/pretalx.py

@@ -95,8 +95,6 @@ def handle_resources(cls, v) -> list[dict[str, str]] | None:
     @model_validator(mode="before")
     @classmethod
     def process_values(cls, values) -> dict:
-        values["speakers"] = sorted([s["code"] for s in values["speakers"]])
-
         # Set slot information
         if values.get("slot"):
             slot = PretalxSlot.model_validate(values["slot"])