Add retries to `Client` class

[alahiff]

Currently they directly use the requests module.

[AbyAbraham21]

Please can you add some more context?

[alahiff]

From the beginning the Run class did retries when needed using tenacity. However, the Client class didn't have this functionality, e.g. if there is a transient network issue the Client method will fail. It might be nice if there were retries - the first rule of clients talking to remote servers is that they should retry.

I'm not sure of the status of the new rewritten Client.