Update ember-cli-babel to 7.7.3
Update ember-cli-babel to 7.7.3

Babel at version 7.4 was not compatible with decorators resulting
in the following eror:
Build Error
(broccoli-persistent-filter:Babel > [Babel: explorviz-frontend])
in explorviz-frontend/components/page-setup/navbar-adv.ts

explorviz-frontend/components/page-setup/navbar-adv.ts:
Support for the experimental syntax 'decorators-legacy'
isn't currently enabled (10:3)

This is fixed with the newest version.

ExplorViz/explorviz-ui-frontend,ExplorViz/explorviz-ui-frontend,ExplorViz/explorviz-ui-frontend