build: enable unconvert linter (#15456)

* build: enable unconvert linter

 - fixes #15453
 - update code base for failing cases

* cmd/puppeth: replace syscall.Stdin with os.Stdin.Fd() for unconvert linter

eth/downloader/downloader.go

@@ -708,7 +708,7 @@ func (d *Downloader) findAncestor(p *peerConnection, height uint64) (uint64, err
 		ttl := d.requestTTL()
 		timeout := time.After(ttl)
 
-		go p.peer.RequestHeadersByNumber(uint64(check), 1, 0, false)
+		go p.peer.RequestHeadersByNumber(check, 1, 0, false)
 
 		// Wait until a reply arrives to this request
 		for arrived := false; !arrived; {
@@ -1518,7 +1518,7 @@ func (d *Downloader) deliver(id string, destCh chan dataPack, packet dataPack, i
 func (d *Downloader) qosTuner() {
 	for {
 		// Retrieve the current median RTT and integrate into the previoust target RTT
-		rtt := time.Duration(float64(1-qosTuningImpact)*float64(atomic.LoadUint64(&d.rttEstimate)) + qosTuningImpact*float64(d.peers.medianRTT()))
+		rtt := time.Duration((1-qosTuningImpact)*float64(atomic.LoadUint64(&d.rttEstimate)) + qosTuningImpact*float64(d.peers.medianRTT()))
 		atomic.StoreUint64(&d.rttEstimate, uint64(rtt))
 
 		// A new RTT cycle passed, increase our confidence in the estimated RTT

eth/downloader/fakepeer.go

@@ -62,7 +62,7 @@ func (p *FakePeer) RequestHeadersByHash(hash common.Hash, amount int, skip int,
 		number := origin.Number.Uint64()
 		headers = append(headers, origin)
 		if reverse {
-			for i := 0; i < int(skip)+1; i++ {
+			for i := 0; i <= skip; i++ {
 				if header := p.hc.GetHeader(hash, number); header != nil {
 					hash = header.ParentHash
 					number--

eth/filters/filter.go

@@ -206,7 +206,7 @@ func (f *Filter) checkMatches(ctx context.Context, header *types.Header) (logs [
 	}
 	var unfiltered []*types.Log
 	for _, receipt := range receipts {
-		unfiltered = append(unfiltered, ([]*types.Log)(receipt.Logs)...)
+		unfiltered = append(unfiltered, receipt.Logs...)
 	}
 	logs = filterLogs(unfiltered, nil, nil, f.addresses, f.topics)
 	if len(logs) > 0 {