fix: price-feeder: correct kraken timestamp unit (#607)

## Description

Kraken's candle timestamps come in as seconds, not milliseconds, so we need to convert it like we do with huobi. 

Fixes an issue where kraken's candle history was being shortened to the most recent one, making tvwap inaccurate. 

----

### Author Checklist

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- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
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- [ ] added a changelog entry to `CHANGELOG.md`
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- [ ] updated the relevant documentation or specification
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- [ ] confirmed `!` in the type prefix if API or client breaking change
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price-feeder/CHANGELOG.md

@@ -62,6 +62,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 - [#552](https://github.com/umee-network/umee/pull/552) Stop requiring telemetry during config validation.
 - [#574](https://github.com/umee-network/umee/pull/574) Stop registering metrics endpoint if telemetry is disabled.
 - [#573](https://github.com/umee-network/umee/pull/573) Strengthen CORS settings.
+- [#607](https://github.com/umee-network/umee/pull/607) Fix kraken provider timestamp unit.
 
 ### Refactor
 

price-feeder/oracle/provider/huobi.go

@@ -267,8 +267,8 @@ func (p *HuobiProvider) setTickerPair(ticker HuobiTicker) {
 func (p *HuobiProvider) setCandlePair(candle HuobiCandle) {
 	p.mtx.Lock()
 	defer p.mtx.Unlock()
-	// huobi time period comes in seconds
-	candle.Tick.TimeStamp = candle.Tick.TimeStamp * 1000
+	// convert huobi timestamp seconds -> milliseconds
+	candle.Tick.TimeStamp = candle.Tick.TimeStamp * int64(time.Second/time.Millisecond)
 	staleTime := PastUnixTime(providerCandlePeriod)
 	candleList := []HuobiCandle{}
 	candleList = append(candleList, candle)

price-feeder/oracle/provider/kraken.go

@@ -482,6 +482,8 @@ func (p *KrakenProvider) setTickerPair(symbol string, ticker TickerPrice) {
 func (p *KrakenProvider) setCandlePair(candle KrakenCandle) {
 	p.mtx.Lock()
 	defer p.mtx.Unlock()
+	// convert kraken timestamp seconds -> milliseconds
+	candle.TimeStamp = candle.TimeStamp * int64(time.Second/time.Millisecond)
 	staleTime := PastUnixTime(providerCandlePeriod)
 	candleList := []KrakenCandle{}
 

price-feeder/oracle/provider/provider.go

@@ -89,5 +89,5 @@ func newCandlePrice(provider, symbol, lastPrice, volume string, timeStamp int64)
 // PastUnixTime returns a millisecond timestamp that represents the unix time
 // minus t.
 func PastUnixTime(t time.Duration) int64 {
-	return time.Now().Add(t*-1).Unix() * 1000
+	return time.Now().Add(t*-1).Unix() * int64(time.Second/time.Millisecond)
 }