chore(deps-dev): bump @storybook/addon-knobs from 6.1.18 to 6.1.21 (#1446)

Bumps [@storybook/addon-knobs](https://github.com/storybookjs/storybook/tree/HEAD/addons/knobs) from 6.1.18 to 6.1.21.
- [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/v6.1.21/addons/knobs)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: [ Cassondra ] <[email protected]>

Author: 3 people