Update CI
On top of !22 (merged),
- resurrect the CI, and update LCG pointers to 104a_cuda (fixes #1 (closed))
- lazy creation of RDF graph, so that they're not created at all if the plots are already cached
- fix most examples from the CI (but the one of the datacards is still broken)
- code format (
make py-checks; make code-format)