We have python application made 4 years old ago . this application work with python 3.6 right now and we have requirements.txt file. and we go to the folder of this application ans make virtual environment by python and after that use source for activate it. and after that we use pip3.6 for install requirements of this project and after make we run this project by uwsgi and run it by Nginx.
Right now we want make this project by python 3.9
our problem is requirement , some of these requirement is not compatible by new python 3.9 and its pip packages.
How we can solve this problem and compatible this project by python 3.9 and new pip packages?