error with a github action formatter error

My `composer.json`:

any change in the composer.json without a updated composer.lock

When I run this command:

```
composer validate
```

within a github action

I get the following output:

the error reported is not in github actions format, therefore you need to open the github actions log and look into the actual log


but I expected a github action formatted error, which would automatically show up in the files-changed tab.

example implementation for the github action error format can be found in `cs2pr`:
https://github.com/staabm/annotate-pull-request-from-checkstyle/blob/b824adfd29a6e6a900de976b5c893c62ce66edca/cs2pr#L131-L150