chore: update ruff requirement from >=0.15.22 to >=0.16.0 (#356)
Rebased onto main by hand: the Coverage job auto-commits a regenerated
assets/coverage-map.svg into every PR branch, which counts as an outside
edit, so Dependabot declines to rebase its own PRs here.
Co-authored-by: Ilya I. Nikitin <ilya.i.nikitin@proton.me>