Fix golangci-lint issues

cmd/litestream/main.go

@@ -96,6 +96,7 @@ func (m *Main) Run(ctx context.Context, args []string) (err error) {
 
 		// Setup signal handler.
 		ctx, cancel := context.WithCancel(ctx)
+		defer cancel()
 		signalCh := make(chan os.Signal, 1)
 		signal.Notify(signalCh, notifySignals...)
 

cmd/litestream/restore.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"io"
@@ -276,5 +275,3 @@ Examples:
 		DefaultConfigPath(),
 	)
 }
-
-var errSkipDBExists = errors.New("database already exists, skipping")