v0.4.0

What's Changed

• Response Streaming by @commonism in #144
• PDM - update dependencies by @github-actions in #133
• model - discriminated unions with parent properties by @commonism in #149
• prepare 0.4.0 by @commonism in #150
• license - restore BSD-3-Clause by @commonism in #151
• release - prepare 0.4.0a3 by @commonism in #152
• release 0.4.0 by @commonism in #155

Full Changelog: v0.3.0...v0.4.0