bug: plugin version setting validation

### Describe the Bug

asdf should display error message if set version do not exist

```shell
asdf set --home scarb 2.92
```
do not produce any output

```shell
asdf set --home scarb 2.9.2
```
this one should work

### Steps to Reproduce

```shell
asdf set --home scarb 2.92
```

### Expected Behaviour

Any error message

### Actual Behaviour

Blank

### Environment

```shell
macos
```

### asdf plugins affected (if relevant)

_No response_

Start by reproducing the `asdf set --home scarb 2.92` and `asdf set --home scarb 2.9.2` commands, then trace the `set` CLI entry point and its plugin-version validation path. Done means an invalid version produces an error message while the valid version continues to work; no specific file or test is named in the issue.

Written by the indexing model from the issue text.