Bump @storybook/angular from 7.6.20 to 8.4.7

Bumps [@storybook/angular](https://github.com/storybookjs/storybook/tree/HEAD/code/frameworks/angular) from 7.6.20 to 8.4.7.
- [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/v8.4.7/code/frameworks/angular)

---
updated-dependencies:
- dependency-name: "@storybook/angular"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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