Update duroxide to 0.1.30

[pinodeca]

Summary

• update the Rust duroxide dependency from 0.1.29 to 0.1.30
• document the upgrade in the changelog
• declare the existing python-dotenv test dependency in the dev extra so fresh test environments are reproducible

Local validation

• cargo clippy --all-targets (zero warnings)
• maturin develop --uv and package import on CPython 3.12
• pytest -ra against PostgreSQL 16: 153 passed, 0 skipped
• maturin build --release plus fresh-environment Linux x86_64 wheel smoke: SQLite orchestration completed with the expected output
• SDK symmetry check: sibling duroxide-node passed cargo clippy --all-targets against duroxide 0.1.30

CI validation

• release wheels built successfully for Linux x86_64/ARM64, macOS x86_64/ARM64, and Windows x86_64
• source distribution built successfully
• local-wheel smoke passed on Windows with Python 3.12
• post-publish registry smoke is release-only and was skipped as expected