Restrict TRT autoinstall to Linux-only

[glenn-jocher]

May partially resolve concerns in #7537 (comment)

🛠️ PR Summary

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🌟 Summary

Enhanced export.py to conditionally check nvidia-tensorrt requirements based on the operating system.

📊 Key Changes

• Added a conditional check to ensure nvidia-tensorrt requirements are only verified on Linux systems.

🎯 Purpose & Impact

• 🛠️ Purpose: The adjustment is made to prevent irrelevant requirement checks on non-Linux systems which do not support nvidia-tensorrt. This targets avoiding errors or confusion when exporting models on those platforms.
• 🔍 Impact: Users on non-Linux systems will experience a smoother export process without facing errors related to missing TensorRT libraries, which are not applicable to their operating system. This makes the export script more robust and user-friendly for a wider audience.