adds retryablehttp client in place of standard

[simpixelated]

retryablehttp performs automatic retries under certain conditions

https://pkg.go.dev/github.com/hashicorp/go-retryablehttp

It's not clear to me if it will handle 429 by default, but it says this about the DefaultBackoff function:

DefaultBackoff provides a default callback for Client.Backoff which will perform exponential backoff based on the attempt number and limited by the provided minimum and maximum durations.

It also tries to parse Retry-After response header when a http.StatusTooManyRequests (HTTP Code 429) is found in the resp parameter. Hence it will return the number of seconds the server states it may be ready to process more requests from this client.

WIP: figuring out how to write tests in go to verify this is working...

[simpixelated]

custom client is enabled by this in the public-api go sdk