It was a long time to do this for me due to lack of time and intemidation of errors.
During the 30th of April and 1st of May holidays, I decided to do this and it turned out not verfy complicated. Here is the steps:
- push the current code into gitlab repo.
- clone it into dev machine
- dump postgres database to dev machine
- use py2to3 module to convert the code
- and most are done
- push code on gitlab again and update server python/libs for this new version.