http.get does not support exponential backoff on retries

[westonsteimel]

What happened:

retry_with_backoff did an exponential backoff on retries, but the newer https://github.com/anchore/vunnel/blob/main/src/vunnel/utils/http.py#L11 just does a static wait between retries. The exponential backoff is important for providers like NVD

What you expected to happen:

http.get supports an exponential backoff and does it by default