chore(deps-dev): bump @storybook/theming from 7.6.17 to 8.4.6

Bumps [@storybook/theming](https://github.com/storybookjs/storybook/tree/HEAD/code/lib/theming) from 7.6.17 to 8.4.6.
- [Release notes](https://github.com/storybookjs/storybook/releases)
- [Commits](https://github.com/storybookjs/storybook/commits/v8.4.6/code/lib/theming)

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

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