Make use of secret-manager while using weather-dl for license keys.

As part of our current data download process for the `weather-dl`, we are not using [secret-manager](https://cloud.google.com/secret-manager) services. This poses a potential security risk, as the sensitive configuration data stored in the config file could be inadvertently leaked, resulting in public access to our API keys and other credentials.

To ensure the security of our licenses and sensitive configuration data, we should integrate the Secret Manager service into the `weather-dl` application. This will allow us to securely manage and retrieve API keys, URLs, and other credentials used during the data download process.