Fix dead download button image link

[hughns]

Pull Request Checklist

• [ ] I read the contributing guide
• [ ] UI change has been tested on both light and dark themes, in portrait and landscape orientations and on iPhone and iPad simulators
• [ ] Accessibility has been taken into account.

• [ ] Pull request is based on the develop branch

• [ ] Pull request contains a changelog file in ./changelog.d
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• [ ] Pull request includes screenshots or videos of UI changes
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