[red-knot] follow simple assignments

[carljm]

trafficstars

Summary

Follow simple assignments in type resolution.

Test Plan

cargo test

[github-actions[bot]]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[MichaReiser]

You know have to label your PRs or they'll show up in the changelog :laughing:

[carljm]

Ugh, yes I know, I did remember to label one of them today! https://github.com/astral-sh/ruff/pull/11176

[carljm]

I think I would have remembered before merging :)