tomllib is only in the stdlib from 3.11 onward. Fall back to the tomli
shim (already a transitive dep) so the regression test can import on
the 3.10 leg of the test matrix.
Issue #5520 reported that crewai 1.13.0 pinned uv 0.9.30, which is
affected by GHSA-pjjw-68hj-v9mw (wheel RECORD path traversal on
uninstall). The pin was bumped to uv>=0.11.6 in 62484934c, and the
workspace already declares a matching override-dependency. Add a
regression test that parses both pyproject.toml files and fails if
either allows a uv version below 0.11.6, so this advisory cannot
re-enter the supply chain silently.
