CI For install instructions

[leshy]

Run actual installation in CI (nightly or on main merge) notify on discord

these are a few installations, mac, ubuntu, nix, as pip package or as git checkout

[Dreamsorcerer]

What are we actually validating with this?

[leshy]

that installation instructions aren't broken, (which is what happened in many places recently) - we'd like to autoinstall & run a replay

[Dreamsorcerer]

How about a smoke test after pushing a release?

[leshy]

we'd like to test both, main should have up to date readme also.. any issue with this? I figure if we have the test we can choose when/where to run