Convert fletapp to the current version of Flet

[Alexukg]

Flet is actively being developed, and its property names and methods often change,
maybe add a command for the upgrade:

flet upgrade [script]

to automatically convert fletapp to the current version of Flet

[justinodi23]

I think this too as a good idea

[ne4sp]

Your mean update script of ypur application? That`s impossible, cause your code have dependencies, and u can use old controls, with another type mb.

By the way, pip install 'flet[all]' --upgrade will upgrade current package, and you can debug your code for bugs.