Make CI faster

[y26805]

Currently build is quite slow (> 8m), and if a test fails we need to re-try the entire job.

This PR aims to make builds faster, by

• checking in poetry.lock for faster package resolution
• caching
• parallelizing tests
• separating build/test steps in the workflow (to make retries easier and faster)
  

[ojii]

• checking in poetry.lock for faster package resolution

I do not like this for libraries. CI should run against the latest versions

[ojii]

I wonder if we should just port this to GHA like I did for aiodynamo. There I also made it so poetry only locks in one step that is re-used by the rest.

[y26805]

• checking in poetry.lock for faster package resolution

I do not like this for libraries. CI should run against the latest versions

yeah thats fair

[y26805]

I wonder if we should just port this to GHA like I did for aiodynamo. There I also made it so poetry only locks in one step that is re-used by the rest.

yeah GHA could work too.. whichever CI tool we use though, think we should separate out browser tests (relatively flaky) vs other tests