Recent swh-web dependencies upgrade broke the tests:
- pip new resolver and its backtracking process now ends up installing pybadges 1.0 instead of pybadges 2.2.1 (I did not look at the details but some transitive dependencies must have pinned pybadges version)
- django-webpack-loader 1.0 got released, it expects a JSON schema for the webpack stats file different than in previous releases
That diff fixes all new errors that were raised since these depencencies upgrade.
django-webpack-loader 1.0 is not packaged in debian and will surely be not distributed in buster
so we will have to package it ourselves (T3330).