Update README.md

[glenn-jocher]

🛠️ PR Summary

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🌟 Summary

Updated code examples in README to use double quotes consistently.

📊 Key Changes

• Changed single quotes to double quotes in the instantiation of the YOLOv8n model.
• Updated the file path in the example to use double quotes.

🎯 Purpose & Impact

• Consistency: Ensures code style consistency throughout the documentation, making examples cleaner and easier to follow.
• Readability: Double quotes are a common standard in many coding styles, potentially improving readability for a broader audience.
• No direct impact on users: These changes are purely stylistic and don't affect the functionality of the code or the performance of the models. Users can expect the same performance and outcomes when running the updated examples.