refactor: mktemp POSIX violation

[71zenith]

Pull Request Template

Type of change

• [ ] Bug fix
• [ ] Feature
• [ ] Documentation update

Description

ramble here

Checklist

• [ ] any anime playing

• [ ] bumped version

• [ ] next, prev and replay work
• [ ] -c history and continue work
• [ ] -d downloads work
• [ ] -s syncplay works
• [ ] -q quality works
• [ ] -v vlc works
• [ ] -e select episode works
• [ ] -S select index works
• [ ] -r range selection works
• [ ] --dub and regular (sub) mode both work

• [ ] all providers return links (not necessarily on a single anime, use debug mode to confirm)

• [ ] -h help info is up to date
• [ ] Readme is up to date
• [ ] Man page is up to date

Additional Testcases

• The safe bet: One Piece
• Episode 0: Saenai Heroine no Sodatekata ♭
• Unicode: Saenai Heroine no Sodatekata ♭
• Non-whole episodes: Tensei shitara slime datta ken (ep. 24.5, ep. 24.9)