chore(deps-dev): bump @storybook/addon-essentials from 6.1.18 to 6.1.20 (#314)

Bumps [@storybook/addon-essentials](https://github.com/storybookjs/storybook/tree/HEAD/addons/essentials) from 6.1.18 to 6.1.20.
- [Release notes](https://github.com/storybookjs/storybook/releases)
- [Changelog](https://github.com/storybookjs/storybook/blob/next/CHANGELOG.md)
- [Commits](https://github.com/storybookjs/storybook/commits/v6.1.20/addons/essentials)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]