Fix pywin32 to only install on Windows

Author: AjitPadhi-Microsoft

src/ContentProcessorAPI/requirements.txt

@@ -134,7 +134,7 @@ python-dotenv==1.1.1
     #   uvicorn
 python-multipart==0.0.20
     # via fastapi
-pywin32==308
+pywin32==308 ; sys_platform == 'win32'
     # via portalocker
 pyyaml==6.0.2
     # via uvicorn