chore(deps-dev): bump @storybook/addon-storysource

Bumps [@storybook/addon-storysource](https://github.com/storybookjs/storybook/tree/HEAD/addons/storysource) from 6.2.0-rc.4 to 6.2.0-rc.6.
- [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/v6.2.0-rc.6/addons/storysource)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -74,7 +74,7 @@
  "@storybook/addon-essentials": "6.2.0-rc.4",
  "@storybook/addon-storyshots": "6.2.0-beta.5",
  "@storybook/addon-storyshots-puppeteer": "6.2.0-beta.5",
- "@storybook/addon-storysource": "6.2.0-rc.4",
+ "@storybook/addon-storysource": "6.2.0-rc.6",
  "@storybook/addons": "6.2.0-rc.6",
  "@storybook/builder-webpack5": "6.2.0-beta.1",
  "@storybook/client-api": "6.2.0-rc.6",