chore: rerun release-plz after closing stale v2.1.1 PR (#143)

The previous release-plz CI run aborted with HTTP 422 because the
stale PR #143 ("chore: release v2.1.1" from 2026-05-13, predating
the v3.x manual publishes) was still open and conflicted with the
fresh v3.1.2 PR release-plz wanted to create. PR #143 has been
closed and its branch deleted; this empty commit re-triggers the
release-plz workflow so it can open a clean release PR for the two
fix commits that landed since v3.1.1.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 1313