feat: add litmus_auth interface spec

[michaeldmitry]

Adds an interface specification and schema for a new litmus_auth interface, used by Litmus auth and backend to communicate to each other their gRPC server endpoints.

[PietroPasotti]

@james-garner-canonical

[james-garner-canonical]

This looks good to me, but for some reason no tests seem to be collected when I try running the interface tests from this branch (run) -- any ideas?

Also if there's an interface library, let's mention it at the start of the readme.

[michaeldmitry]

This looks good to me, but for some reason no tests seem to be collected when I try running the interface tests from this branch (run) -- any ideas?

Also if there's an interface library, let's mention it at the start of the readme.

@james-garner-canonical I updated this PR with a temp branch that has the tests, but the CI doesn't seem to pick it up tho.
It passes locally. Is it because of the Python version maybe?

[michaeldmitry]

@james-garner-canonical after trying to run the workflow from this branch , we get a diff error. That error is probably due to setting up python 3.8 in the workflow.

[james-garner-canonical]

Progress! We're now failing to install dependencies because Python 3.10 is too low 😃

[michaeldmitry]

Progress! We're now failing to install dependencies because Python 3.10 is too low 😃

Yeah the lib needs python ~= 3.12.0

[james-garner-canonical]

Great, tests pass with Python 3.12!