chore(main): release 3.9.0

[mixie-bot[bot]]

:robot: I have created a release beep boop

3.9.0 (2023-07-20)

Features

• add Contentstack support (#77) (eaf33b7)

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[mixie-bot[bot]]

:robot: Release is at https://github.com/ascorbic/unpic/releases/tag/v3.9.0 :sunflower: