* accounts/scwallet: remove unnecessary uses of fmt.Sprintf

* cmd/puppeth: remove unnecessary uses of fmt.Sprintf

* p2p/discv5: remove unnecessary use of fmt.Sprintf

* whisper/mailserver: remove unnecessary uses of fmt.Sprintf

* core: goimports -w tx_pool_test.go

* eth/downloader: goimports -w downloader_test.go

* build: upgrade to golangci-lint 1.24.0