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:

  1. push the current code into gitlab repo.
  2. clone it into dev machine
  3. dump postgres database to dev machine
  4. use py2to3 module to convert the code
  5. and most are done
  6. push code on gitlab again and update server python/libs for this new version.

That's it!