Add query for production and generation units

[tuxiano]

Hi,

I am working on adding a query for production and generation units based on the GET Production and Generation Units API.

To achieve this, I have created a fork and a branch with the new query implementation.

However, I encountered an issue with the unit tests failing due to a missing module, "settings". Could you advise on where to obtain this module or how to resolve this dependency?

Additionally, I would appreciate guidance on selecting an appropriate function in EntsoePandasClient that could serve as a template for parsing the response from EntsoeRawClient.

Thank you for your time and support!

Best regards,
tuxiano