Write a function to sort a list of patient records based on a specific field.
Implement sort_records(records, field). records is a list of dictionaries, and field is a key present in every dictionary. Return a new list sorted in ascending order by that field, without modifying the input list. If multiple records have the same value, preserve their original relative order.
Function signature: def sort_records(records, field):
def sort_records(records, field):