Bump storybook from 8.6.0 to 8.6.15

Bumps [storybook](https://github.com/storybookjs/storybook/tree/HEAD/code/core) from 8.6.0 to 8.6.15.
- [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/v8.6.15/code/core)

---
updated-dependencies:
- dependency-name: storybook
  dependency-version: 8.6.15
  dependency-type: direct:development
...

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

Author: dependabot[bot]

packages/next/package.json

@@ -322,7 +322,7 @@
     "source-map-loader": "5.0.0",
     "source-map08": "npm:source-map@0.8.0-beta.0",
     "stacktrace-parser": "0.1.10",
-    "storybook": "8.6.0",
+    "storybook": "8.6.15",
     "stream-browserify": "3.0.0",
     "stream-http": "3.1.1",
     "strict-event-emitter": "0.5.0",