dev: price-pusher data fetching

[EvolveArt]

Current Behavior

Right now the API fetching is the main bottleneck of the off-chain price pusher with ~300 pairs.
Data fetching blocks the thread of publishing i.e we wait till we have fetched all the latest data before publishing.

Expected Behavior

• We could push one by one i.e as soon as we fetch an asset we publish the result off-chain
• If we get to that, we might get rate-limited so we need to work around this
• In any case, we should have a lower latency otherwise the StarkEx endpoint doesnt send back fresh data