🧹 [code health] Remove unused import sys from apnea_screener.py

[manupawickramasinghe]

🎯 What: Removed unused import sys from examples/sleep/apnea_screener.py.
💡 Why: To improve code health and readability by removing an unused import.
✅ Verification: Verified that the file has no syntax errors using python3 -m py_compile examples/sleep/apnea_screener.py and that the test_docker_entrypoint.sh tests continue to pass.
✨ Result: Improved maintainability of the codebase without changing functionality.

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PR created automatically by Jules for task 4385379294756261718 started by @manupawickramasinghe

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