Bump amplitude-js from 8.13.0 to 8.15.0 in /website

Bumps [amplitude-js](https://github.com/amplitude/amplitude-javascript) from 8.13.0 to 8.15.0.
- [Release notes](https://github.com/amplitude/amplitude-javascript/releases)
- [Changelog](https://github.com/amplitude/Amplitude-JavaScript/blob/main/CHANGELOG.md)
- [Commits](https://github.com/amplitude/amplitude-javascript/compare/v8.13.0...v8.15.0)

---
updated-dependencies:
- dependency-name: amplitude-js
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

website/package.json

@@ -22,7 +22,7 @@
     "@docusaurus/preset-classic": "^2.0.0-beta.9",
     "@mdx-js/react": "^1.6.21",
     "@svgr/webpack": "^5.5.0",
-    "amplitude-js": "^8.13.0",
+    "amplitude-js": "^8.15.0",
     "clsx": "^1.1.1",
     "docusaurus-plugin-sass": "^0.2.1",
     "docusaurus2-dotenv": "^1.4.0",