Upgrade the existing web based workflow tool

Current stack:
Current tool runs on an A2 account
in PHP 5.6.40 built with CodeIgniter 3.0 in the backend
and Bootstrap 3 in the frontend

Requirements:
Our web based workflow tool code needs to be updated to
the latest version of PHP or Python as well
as a suitable framework, using bootstrap in
the front end to duplicate as much as
possible its current style. Once the above is accomplished,
The tool will require regular updates and materials