flask safe filename - secure_filename

参考： - https://flask.palletsprojects.com/en/2.3.x/patterns/fileuploads/ - https://tedboy.github.io/flask/generated/werkzeug.secure_filename.html

>>> from werkzeug.utils import secure_filename
>>> secure_filename("My cool movie.mov")
'My_cool_movie.mov'
>>> secure_filename("../../../etc/passwd")
'etc_passwd'
>>> secure_filename(u'i contain cool \xfcml\xe4uts.txt')
'i_contain_cool_umlauts.txt'