Bump prismjs, @storybook/addon-knobs and @storybook/react

Removes [prismjs](https://github.com/PrismJS/prism). It's no longer used after updating ancestor dependencies [prismjs](https://github.com/PrismJS/prism), [@storybook/addon-knobs](https://github.com/storybookjs/addon-knobs) and [@storybook/react](https://github.com/storybookjs/storybook/tree/HEAD/app/react). These dependencies need to be updated together.


Removes `prismjs`

Updates `@storybook/addon-knobs` from 5.0.6 to 6.4.0
- [Release notes](https://github.com/storybookjs/addon-knobs/releases)
- [Changelog](https://github.com/storybookjs/addon-knobs/blob/v6.4.0/CHANGELOG.md)
- [Commits](https://github.com/storybookjs/addon-knobs/commits/v6.4.0)

Updates `@storybook/react` from 5.0.6 to 6.5.12
- [Release notes](https://github.com/storybookjs/storybook/releases)
- [Changelog](https://github.com/storybookjs/storybook/blob/v6.5.12/CHANGELOG.md)
- [Commits](https://github.com/storybookjs/storybook/commits/v6.5.12/app/react)

---
updated-dependencies:
- dependency-name: prismjs
  dependency-type: indirect
- dependency-name: "@storybook/addon-knobs"
  dependency-type: direct:development
- dependency-name: "@storybook/react"
  dependency-type: direct:development
...

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