update results download csv to match Executive Order guidance wrt gender

[mirrorstage]

A column name in the simplereport-test-results.csv is not following the required pattern.

Steps to reproduce:

• in the demo environment, navigate to the Results tab
• click the `Download results' button
• the CSV file downloads
• open the file, and scroll to the right until you reach column AG

Expected: column name is Patient sex Found: column name is "Patient gender`