fix: remove unnecessary fresh price filtering (#103)

This change removes a check in the code that does not allow multiple
updates within the same timestamp to passthrough. `last_info.timestamp`
is always less than or equal to `info.timestamp`. So, this condition
`last_info.timestamp < info.timestamp` filters newer updates in the same
timestamp and essentially caps our publishing frequency to 1s. It was
intended to work for Solana but the publishing frequency itself takes
care of it. This change might result in increased Sol burn but the
actions to reduce it should be reducing the frequency. Please note that
in some filterings after, the same update prices are ignored so most of
the fee savings should remain there.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "pyth-agent"
-version = "2.4.4"
+version = "2.4.5"
 edition = "2021"
 
 [[bin]]

src/agent/solana/exporter.rs

@@ -436,14 +436,6 @@ impl Exporter {
         // and to ignore stale information.
         let fresh_updates = local_store_contents
             .into_iter()
-            .filter(|(identifier, info)| {
-                // Filter out timestamps older than what we already published
-                if let Some(last_info) = self.last_published_state.get(identifier) {
-                    last_info.timestamp < info.timestamp
-                } else {
-                    true // No prior data found, letting the price through
-                }
-            })
             .filter(|(_identifier, info)| {
                 // Filter out timestamps that are old
                 (now - info.timestamp) < self.config.staleness_threshold.as_secs() as i64
@@ -452,7 +444,7 @@ impl Exporter {
                 // Filter out unchanged price data if the max delay wasn't reached
 
                 if let Some(last_info) = self.last_published_state.get(identifier) {
-                    if (info.timestamp - last_info.timestamp)
+                    if info.timestamp.saturating_sub(last_info.timestamp)
                         > self.config.unchanged_publish_threshold.as_secs() as i64
                     {
                         true // max delay since last published state reached, we publish anyway