Replace print calls by logger calls

[unkindypie]

When during handing of a notification an error occures, it's printed using print function. As the library has built-in logger class which can be extended and injected by client code, it's better to replace print calls with logger calls. It will allow client-side loggers capture exceptions inside notification handlers. Also, it will be helpful if Mediator class will also pass exception stack trace to the logger.
Reference to the file with an issue:
https://github.com/ozgurkara/pydiator-core/blob/5aec2f61c8489210135dc69f35ed5f1a600551a0/pydiator_core/mediatr.py#L53C1-L54C1