W&B config warnings when training a sweep agent

[Adamits]

Currently, when training a sweep agent, we need to start the agent within a hyperparameter config, which automatically logs all of the hyperparameters to W&B. We also need to initialize the pytorch-lightning WandbLogger, which under the hood attempts to log the config again. See here for details: wandb/wandb#2641.

Ideally, we would solve this by not updating twice, however, this may be out of our control as we rely on wandb and pytorch-lightning for those behaviors.

A work-around is to suppress the W&B warning message. So far, warnings.filterwarnings does not work -- but we should investigate this more.