Resolve "Passport generator fails when gender = diverse"

Closes #665 (closed)

What does this MR do?

Fixes the issue during generation of passports when using the diverse gender (Index 3)

How confident are you it won't break things if deployed?

Should not cause major problems

Links to related issues

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Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))