Adapt to upstream changes in typer autocomplete interface.

[bckohan]

shell_complete may be going away in future versions of Typer.

I am hoping my PR will be accepted which should minimize impacts to django-typer.

[bckohan]

This should not hold up the 3.0 release any longer. It is unclear when upstream will merge my changes.

I've gone back and forth on this - but the breaking change upstream (shell_complete -> autocompletion) will not trigger a major version change on django-typer. We'll keep the dependencies tight and when this change happens we'll issue a feature release. This might break some projects that are using semantic versioning discipline on just django-typer but not also typer itself. It is what it is, I'm tired of waiting.

I think this is ok because the break will happen on a typer interface not a django-typer interface. Hopefully not many people are using the shell_complete features yet anyway...