fix: typo of onChange func parameter on cascader basic example

[CarlaPaiva]

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
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• Site / documentation update
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🔗 Related issue link

#47336

💡 Background and solution

It fixes the proved parameter of the onChange function of Cascader's basic demo to match the example interface example.

📝 Changelog

Language	Changelog
🇺🇸 English	Updated basic demo of Cascader component.
🇨🇳 Chinese	更新了级联组件的基本演示。

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

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👁 Visual Regression Report for PR #47427 Passed ✅

🎯 Target branch: master (ae9e25f)
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Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ae9e25f) 100.00% compared to head (e679018) 100.00%.

Additional details and impacted files

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  Files          734       734           
  Lines        12593     12593           
  Branches      3298      3298           
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  Hits         12593     12593           

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