NPM hangs

For the last few commits the Travis CI build failed while running `npm install`. For example [here](https://app.travis-ci.com/github/graphhopper/graphhopper/builds/250736850)



```

[INFO] --- frontend-maven-plugin:1.10.0:npm (npm install) @ graphhopper-web-bundle ---



[INFO] Running 'npm install' in /home/travis/build/graphhopper/graphhopper/web-bundle



[INFO] npm WARN deprecated chokidar@2.1.8: Chokidar 2 does not receive security updates since 2019. Upgrade to chokidar 3 with 15x fewer dependencies



[INFO] npm WARN deprecated opn@6.0.0: The package has been renamed to `open`



[INFO] npm WARN deprecated fsevents@1.2.13: fsevents 1 will break on node v14+ and could be using insecure binaries. Upgrade to fsevents 2.



[INFO] npm WARN deprecated vector-tile@1.3.0: This module has moved: please install @mapbox/vector-tile instead



[INFO] npm WARN deprecated uuid@3.4.0: Please upgrade  to version 7 or higher.  Older versions may use Math.random() in certain circumstances, which is known to be problematic.  See https://v8.dev/blog/math-random for details.



[INFO] npm WARN deprecated querystring@0.2.0: The querystring API is considered Legacy. new code should use the URLSearchParams API instead.



[INFO] npm WARN deprecated point-geometry@0.0.0: This module has moved: please install @mapbox/point-geometry instead



[INFO] npm WARN deprecated source-map-resolve@0.5.3: See https://github.com/lydell/source-map-resolve#deprecated



[INFO] npm WARN deprecated minimatch@0.3.0: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue



[INFO] npm WARN deprecated source-map-url@0.4.1: See https://github.com/lydell/source-map-url#deprecated



[INFO] npm WARN deprecated resolve-url@0.2.1: https://github.com/lydell/resolve-url#deprecated



[INFO] npm WARN deprecated urix@0.1.0: Please see https://github.com/lydell/urix#deprecated



No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.



Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#build-times-out-because-no-output-was-received



The build has been terminated

```



Apparently the `npm install` command hangs for some reason so the build times out after ten minutes.

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