chore: Python 3.12 is the floor, part B (#6)

check now requires requires-python >= 3.12. Every standard driver moved
to that floor in its own PR, so none of them goes red with this.

CHANGELOG.md

@@ -9,8 +9,8 @@ The format follows [Keep a Changelog](https://keepachangelog.com/), versions fol
 - Python 3.12 is the floor: the shared workflow tests on 3.12 and 3.13 by default and
   runs `lowest` on 3.12, the template declares `requires-python = ">=3.12"` with ruff
   and mypy targeting 3.12, and the tool itself needs 3.12. netOrk runs every driver in
-  its own containers on 3.12, so older versions are no longer tested. `check` keeps
-  accepting a 3.10 floor until every driver has moved.
+  its own containers on 3.12, so older versions are no longer tested. `check`
+  requires `requires-python` ≥ 3.12.
 - `check` reports a license given as a TOML table or as a `License ::` classifier:
   setuptools refuses both from 2027-02-18 (PEP 639). The template builds with
   setuptools>=77.