Update the test cases to prevent non-ascii characters in yaml files

[ravench]

NetBox appears to not be able to handle non-ascii characters.
This causes issues when importing devices or modules that contain non-ascii characters.
Those are usually dashes (long, short, ect) and symbols like (r) or (tm).

In a shell, the files at issue can be found using grep:

LC_ALL=C  grep -l "[\x80-\xFF]" ./**/*.yaml 

There should be a test for this. There seems to be no applicable test in pre-commit-hooks and no flag for yamlfmt or yamllint, so handling this in a own hook or in pytest seems to be necessary.

Unfortunately, I don't understand pytest well enough to write my own tests, therefore this is an issue and not a pull request.