Bump @jupyterlab/builder from 4.5.1 to 4.5.6 in /js

Bumps [@jupyterlab/builder](https://github.com/jupyterlab/jupyterlab) from 4.5.1 to 4.5.6.
- [Release notes](https://github.com/jupyterlab/jupyterlab/releases)
- [Changelog](https://github.com/jupyterlab/jupyterlab/blob/main/RELEASE.md)
- [Commits](https://github.com/jupyterlab/jupyterlab/compare/@jupyterlab/builder@4.5.1...@jupyterlab/builder@4.5.6)

---
updated-dependencies:
- dependency-name: "@jupyterlab/builder"
  dependency-version: 4.5.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

js/package.json

@@ -54,7 +54,7 @@
     "@babel/core": "^7.29.0",
     "@babel/eslint-parser": "^7.28.6",
     "@babel/preset-env": "^7.29.0",
-    "@jupyterlab/builder": "^4.5.1",
+    "@jupyterlab/builder": "^4.5.6",
     "babel-jest": "^30.2.0",
     "cpy-cli": "^6.0.0",
     "eslint": "^8.57.1",