@rouja secrets management relies on a central repository, which manages
all numerique-gouv secrets.
I have created a new subfolder in its "numerique-gouv/secret" repository
to store all update key/credentials related to the Meet project.
I have updated all references of "Impress" to "Meet".
Migrations were manually updated and not regenerated. Never-mind,
they all will be squashed before the first release.
I have also searched for reference to "Magnify", and replaced them
by "Meet".
While updating the backend sources, I have also fixed other parts of
the project, namely:
- Compose file
- Github documentation and CI
- Makefile commands
