[red-knot] Add `async-utils` to mypy_primer workflow

[AlexWaygood]

Mypy_primer hasn't had much to say about @dcreager's recent generics work, because we've been doing new-style generics first, and not very many projects "in the wild" use new-style generics yet (they're only valid syntax on Python 3.12+). We should consider adding https://github.com/mikeshardmind/async-utils to our mypy_primer workflow, as it makes use of PEP-695 generics, so will give us valuable signal on how well our implementation is progressing.

This involves either making a PR to https://github.com/hauntsaninja/mypy_primer or our Astral fork (https://github.com/astral-sh/mypy_primer) to add the project to project.py. Then, once that's done, we need to update the workflow here to explicitly select the project during the mypy_primer CI job:

ruff/.github/workflows/mypy_primer.yaml

Line 71 in 058439d

--project-selector '/(mypy_primer|black|pyp|git-revise|zipp|arrow|isort|itsdangerous|rich|packaging|pybind11|pyinstrument|typeshed-stats|scrapy|werkzeug|bidict)$' \

(cc. @sharkdp, who introduced our primer workflow to CI)