Fix pyproject.toml for xai-streamlit

[rabea-al]

Description

This PR fixes metadata issues in the pyproject.toml of xai-streamlit:

• Corrected readme field casing (README.md instead of readme.md).
• Fixed repository URL to point to the correct repo (xai-streamlit).
• Ensured README.md is properly referenced.
• Verified default_example_path points to a valid example

References

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Pull Request Type

• Xircuits Component Library Code
• Workflow Example
• Documentation
• Others (Please Specify)

Type of Change

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Tests

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1. Test A

1. First step
2. Second step
3. ...

Tested on?

• Windows
• Linux Ubuntu
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• Mac
• Others (State here -> xxx )

Notes

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