Avoid cv2 window init code on Windows

[glenn-jocher]

Resolves #8642

🛠️ PR Summary

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🌟 Summary

Improved compatibility for window management on Linux during detection in YOLOv5.

📊 Key Changes

• Imported platform module in detect.py.
• Adjusted window streaming condition to be specific to the Linux operating system.

🎯 Purpose & Impact

• 🐧 Ensures that only on Linux, new windows can be created or resized to display detection results, preventing potential issues on other OS like Windows or MacOS.
• 👀 Enhanced user experience for Linux users by allowing window resizing, aligning the behavior with users' expectations of window management on their OS.
• ✅ This update possibly prevents errors or unexpected behaviors related to window management for users on non-Linux systems.