Fix requirements.txt: Remove invalid python-cors dependency

CORS support is already included in FastAPI via CORSMiddleware.
The python-cors package doesn't exist in PyPI.

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Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

requirements.txt

@@ -16,6 +16,3 @@ mediapipe==0.10.21
 
 # Image processing
 Pillow==10.1.0
-
-# CORS support
-python-cors==1.0.0