Providing config object through a `run_script` throws error

[galamit86]

When the config object is provided at runtime as a parameter through, it becomes a dict somewhere along the process and an error occurs when using dot notation.

When provided as a default in the register_statline_bq script, the issue doe not occur.

Additionally, this feels like the wrong way to go about it - we provide the full prefect config via a parameter, just because we add our config to it. Might be related to #41 as well as #40.