Remove redundant function that was moved to import_helpers file

home/import_assessments.py

@@ -1,6 +1,5 @@
 import contextlib
 import csv
-import re
 from dataclasses import dataclass, field, fields
 from queue import Queue
 from typing import Any
@@ -223,9 +222,6 @@ def validate_headers(self, headers: list[str], row_num: int) -> None:
                 row_num=row_num,
             )
 
-    def to_snake_case(self, s: str) -> str:
-        return re.sub(r"[\W_]+", "_", s).lower().strip("_")
-
 
 # Since wagtail page models are so difficult to create and modify programatically,
 # we instead store all the pages as these shadow objects, which we can then at the end