CSSUTILS logger overrides existing config on import

Hi!

On first import of `cssutils`, the `'CSSUTILS'` logger is set up and configured with some default values, as can be seen here:
https://github.com/jaraco/cssutils/blob/main/cssutils/errorhandler.py#L51-L56

This can lead to issues if your import of `cssutils` happens later than your main logging config setup, since it will override whatever is already configured. To avoid it, you must pre-emptively import `cssutils` before your own logging config.

It would be easier if `cssutils` detected if the logger has already been set up, and didn't add it's own default config in that case. At the very least, if it preserved the loglevel the user has selected that would help.

Leggi le righe 51-56 di cssutils/errorhandler.py e traccia come viene configurato il logger CSSUTILS al primo import. Definisci done come il mantenimento di una configurazione esistente del logger, incluso il livello di log dell’utente, invece di applicare i valori predefiniti; l’issue non indica alcun file di test, quindi individua la copertura esistente pertinente prima di apportare modifiche.

Scritto dal modello di indicizzazione a partire dal testo della issue.