fix: fix AliasRunner import path in README (#120)

[etscript]

📝 PR Type

• Add new sample
• Update existing sample
• Add new test cases
• Fix test failures
• Documentation/Configuration update

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📚 Description

[Please briefly describe the background, changes, and purpose of this PR. For example:

• Added game_werewolves to demonstrate XYZ functionality in agentscope.
• Fixed test failures in game_test.py caused by agentscope interface changes.
• Updated dependency installation instructions in README.md of agentscope-samples.]

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🧪 Testing Validation

[Please explain how to validate the changes:

1. How to run the added/modified test cases?
2. Is integration testing with agentscope required?
3. Has code been formatted (e.g., pre-commit)?]

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✅ Checklist

Please complete the following checks before submitting the PR:

• All sample code has been formatted with pre-commit run --all-files
• All new/modified test cases have passed (run pytest tests/)
• Test coverage has not decreased (if applicable)
• Sample code follows agentscope best practices (e.g., config management, logging)
• Related documentation in agentscope-samples has been updated (e.g., README.md)

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