Update type hint for to_multipart_data method

Co-authored-by: Isak Ohlsson Ångnell <[email protected]>

cg/clients/freshdesk/models.py

@@ -20,7 +20,7 @@ class TicketCreate(BaseModel):
     type: str | None = None
     custom_fields: dict[str, str | int | float | None] = Field(default_factory=dict)
 
-    def to_multipart_data(self) -> list[Tuple[str, Union[str, int, bytes]]]:
+    def to_multipart_data(self) -> list[Tuple[str, str | int | bytes]]:
         """Custom converter to multipart form data."""
         multipart_data = []