chore: release stepflow-py v0.4.0 (#342)

- Bump version from 0.3.0 to 0.4.0
- Update CHANGELOG.md with release notes

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

sdks/python/CHANGELOG.md

@@ -2,6 +2,24 @@
 
 All notable changes to this project will be documented in this file.
 
+## <a id="0.4.0"></a> [Stepflow Python SDK 0.4.0](https://github.com/stepflow-ai/stepflow/releases/tag/stepflow-py-0.4.0) - 2025-10-02
+### Bug Fixes
+
+- Better future management for process messages ([#325](https://github.com/stepflow-ai/stepflow/pull/325))
+
+### Features
+
+- Allow Python components/UDFs to signal skip ([#239](https://github.com/stepflow-ai/stepflow/pull/239))
+- Remove duplicate types ([#240](https://github.com/stepflow-ai/stepflow/pull/240))
+- Get Vector Store Rag flow working ([#309](https://github.com/stepflow-ai/stepflow/pull/309))
+- Add HTTP protocol support for Langflow component server ([#319](https://github.com/stepflow-ai/stepflow/pull/319))
+- Restart stdio subprocess; retry components ([#336](https://github.com/stepflow-ai/stepflow/pull/336))
+
+### Miscellaneous Tasks
+
+- Use workflow rather than repository dispatch ([#237](https://github.com/stepflow-ai/stepflow/pull/237))
+- Add Langflow to CI ([#243](https://github.com/stepflow-ai/stepflow/pull/243))
+
 ## <a id="0.3.0"></a> [Stepflow Python SDK 0.3.0](https://github.com/stepflow-ai/stepflow/releases/tag/stepflow-py-0.3.0) - 2025-08-25
 ### Bug Fixes
 

sdks/python/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "stepflow-py"
-version = "0.3.0"
+version = "0.4.0"
 description = "Python SDK for Stepflow components and workflows."
 readme = "README.md"
 license = {text = "Apache-2.0"}