Python: Bump Python package version to 0.4.2.dev (#4204)

### Motivation and Context

Bumping SK Python package version to 0.4.2.dev for upcoming release.

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### Description

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### Contribution Checklist

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- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

Co-authored-by: Evan Mattson <[email protected]>

python/pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "semantic-kernel"
-version = "0.4.1.dev"
+version = "0.4.2.dev"
 description = ""
 authors = ["Microsoft <[email protected]>"]
 readme = "pip/README.md"