Bump contract and runtime to 0.7.2 / 0.4.0 for the python-csv release

[carolsimone]

Summary

• Bumps continuo-engine-contract 0.7.1 -> 0.7.2 and continuo-python-runtime 0.3.1 -> 0.4.0, mirroring the shape of Bump contract and runtimes #39 (the previous release bump).
• Updates the adapter pins (adapters/postgres/pyproject.toml, adapters/trino/pyproject.toml) and the README/template/Dockerfile image-tag references to the new version, and regenerates uv.lock (version metadata only).
• Contract content is unchanged for this release — the version moves because the tag-triggered publish workflow uploads both packages in the same run, and PyPI rejects a re-upload of an existing version. One tag ships both packages plus both engine images.
• This is the release that ships feat: python-csv node kind (contract-only CSV loader + validation header check) #42 (python-csv node kind).

Test plan

• uv lock regenerated cleanly (version metadata only diff)
• uv sync --all-packages --all-groups
• uv run pytest tests contract/tests -m "not image" -q — 614 passed, 3 deselected
• uv run pytest tests/test_contract_pin_consistency.py tests/test_template.py -v — 6 passed
• uv run ruff check . — clean
• uv run mypy per-package (matching ci.yml) — clean across runtime, contract, postgres adapter, trino adapter

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