cliff complete option is broken with error Unknown shell syntax

Python Version: 3.13.11

Cliff version: 4.13.1

With the latest Python, cliff complete option is broken with error "Unknown shell syntax" because for bash self._formatters[parsed_args.shell].plugin is null.

To handle it, defined new custom class in cliff/complete.py

```
class CustomBashCompletion:
    """Shim to emulate importlib/pkg_resources entry point"""
    def __init__(self, plugin):
        self.plugin = plugin
```

And defined self._formatters = {'bash': CustomBashCompletion(CompleteBash)}, even after doing this an additional change was needed in cliff/display.py.

As formatter_choices[0] was null and hence length checking is needed. If length is 0 return the parser. With this complete option started working.

can you please check this can be taken as official commit?