[NPM package] Add missing peer dependency

[tkohr]

Description

PR adds url to package as a dependency, which is needed by the peer dependency rdflib => @frogcat/ttl2jsonld, but which is not included in the package-lock for some reason. This breaks the app build downstream.

In gn-ui url is already present via @storybook/builder-webpack5.

Quality Assurance Checklist

• Commit history is devoid of any merge commits and readable to facilitate reviews
• If new logic ⚙️ is introduced: unit tests were added
• If new user stories 🤏 are introduced: E2E tests were added
• If new UI components 🕹️ are introduced: corresponding stories in Storybook were created
• If breaking changes 🪚 are introduced: add the breaking change label
• If bugs 🐞 are fixed: add the backport <release branch> label
• The documentation website 📚 has received the love it deserves

---

[github-actions]

Affected libs: , Affected apps: ,

• 🚀 Build and deploy storybook and demo on GitHub Pages
• 📦 Build and push affected docker images

[tkohr]

As this is a known issue, that may potentially be fixed soon, I'll close this PR here and temporarily install the missing dependency downstream.