Retry on failed upload

[kolesnikovae]

Requests failed with codes 5xx and 429 (rate limited) should be retried with exponential backoff interval and max number of attempts per request.

[craigpastro]

If you don't mind letting *resty.Client from https://github.com/go-resty/resty replace *http.Client I think this can be done rather painlessly and nicely. If so I can try a PR.

[kolesnikovae]

As of now pyroscope-go has zero dependencies and is very lightweight. I'm not very sure if adding resty (which is primarily a very feature-rich REST client) exclusively for a basic retry mechanism is worth it

[craigpastro]

Hi @kolesnikovae. Yes, that would be a shame for sure. I know there is some subtlety with retries and trying to use the same connection that one would hope resty deals with (but I haven't actually read the code), but that is probably over thinking it.

[mohammed90]

Hashicorp's package retryablehttp is pretty lightweight in terms of deps.