Python: Increment Python version to 1.12.1. (#9431)

### Motivation and Context

Increment Python version to 1.12.1 for a release.

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### Description

Increment Python version to 1.12.1 for a release.

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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 😄

python/semantic_kernel/__init__.py

@@ -2,5 +2,5 @@
 
 from semantic_kernel.kernel import Kernel
 
-__version__ = "1.12.0"
+__version__ = "1.12.1"
 __all__ = ["Kernel", "__version__"]