CSV filename is too long for Excel

[sjorford]

Excel has a limit of 207 characters (Office365 version 2405 on Windows 11)

Only seems to be an issue when manually selecting a lot of fields rather than a field group - e,g. selecting the "All person fields" checkbox produces this filename: dc-candidates-election_date___ballot_paper_id___election_id_parl2024-07-04__party_id___cancelled___locked___field_group_person-2024-06-16T06-43-19.csv

Deselecting "Statement to voters" and keeping all other person fields selected produces this (truncated) filename: dc-candidates-election_date___ballot_paper_id___election_id_parl2024-07-04__party_id___cancelled___locked___has_email___has_facebook_page_url___has_facebook_personal_url___has_homepage_url___has_blog_url___has_lin.csv

This is only 213 characters long so it only blows the limit by 6