Remove bet_file from back/app.py
Remove bet_file from back/app.py

Signed-off-by: jensenzhang <5bf29d771dfd200e65c24d326e5354a7930fdbd9@gmail.com>

fno2010/smile-to-me,fno2010/smile-to-me,fno2010/smile-to-me,fno2010/smile-to-me,fno2010/smile-to-me