FIX: PyPDF2 error

[Cyb3rC3lt]

Hey,

Just got an error trying to run this on Windows:

"PyPDF2.errors.DeprecationError: addBlankPage is deprecated and was removed in PyPDF2 3.0.0. Use add_blank_page instead."

Adding PyPDF2~=2.0 to requirements.txt fixed it.

Just thought you guys might want to know.