Bump immer, @storybook/addon-docs and @storybook/html

Removes [immer](https://github.com/immerjs/immer). It's no longer used after updating ancestor dependencies [immer](https://github.com/immerjs/immer), [@storybook/addon-docs](https://github.com/storybookjs/storybook/tree/HEAD/addons/docs) and [@storybook/html](https://github.com/storybookjs/storybook/tree/HEAD/app/html). These dependencies need to be updated together.


Removes `immer`

Updates `@storybook/addon-docs` from 6.1.21 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/addons/docs)

Updates `@storybook/html` from 6.1.21 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/html)

---
updated-dependencies:
- dependency-name: immer
  dependency-type: indirect
- dependency-name: "@storybook/addon-docs"
  dependency-type: direct:development
- dependency-name: "@storybook/html"
  dependency-type: direct:development
...

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Author: dependabot[bot]