build(deps): bump @nuxtjs/apollo in /webapp

Bumps [@nuxtjs/apollo](https://github.com/nuxt-community/apollo-module) from 4.0.0-rc19 to 5.0.0-alpha.15.
- [Release notes](https://github.com/nuxt-community/apollo-module/releases)
- [Changelog](https://github.com/nuxt-modules/apollo/blob/v5/CHANGELOG.md)
- [Commits](https://github.com/nuxt-community/apollo-module/compare/v4.0.0-rc.19...v5.0.0-alpha.15)

---
updated-dependencies:
- dependency-name: "@nuxtjs/apollo"
  dependency-version: 5.0.0-alpha.15
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

webapp/package.json

@@ -24,7 +24,7 @@
   "dependencies": {
     "@human-connection/styleguide": "0.5.22",
     "@mapbox/mapbox-gl-geocoder": "^5.0.2",
-    "@nuxtjs/apollo": "^4.0.0-rc19",
+    "@nuxtjs/apollo": "^5.0.0-alpha.15",
     "@nuxtjs/axios": "~5.9.7",
     "@nuxtjs/composition-api": "0.32.0",
     "@nuxtjs/dotenv": "~1.4.1",