feat(app/metrics): support new PAT format

[lowlighter]

Discussed in #1263

Check what needs to be done to support new PAT format with granular rights

[lowlighter]

Not possible (at least for now):
https://docs.github.com/fr/graphql/guides/forming-calls-with-graphql#authenticating-with-graphql

[lowlighter]

github/roadmap#622

[dustessavdh]

It seems like they support fine-grained tokens for authenticating now.
They closed github/roadmap#622 and the docs now state: