Theme UI `<ThemeProvider />` does not work with Storybook

[Nick Taylor]

Describe the bug

The Theme UI <ThemeProvider /> currently will not work with Storybook due to emotion dependency conflicts.

To Reproduce

We're not using the Theme UI <ThemeProvider /> in Storybook yet, but as mentioned above in the description, it's a known issue.

Expected behavior

The fix mentioned in system-ui/theme-ui#1530 (comment) works. I've implemented it in nickytonline/picture-portal@daddb14

Screenshots

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Desktop (please complete the following information):
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Smartphone (please complete the following information):
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Additional context
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