chore: run go modernize tool

This is a fixup of the codebase using:
go run golang.org/x/tools/go/analysis/passes/modernize/cmd/modernize@latest -fix ./...

This has no bahvior changes, and only updates safe changes for
modern go features.

cmd/versitygw/admin.go

@@ -583,11 +583,11 @@ func parseCreateBucketPayload(input string) ([]byte, error) {
 	}
 	for _, part := range inputParts {
 		part = strings.TrimSpace(part)
-		if strings.HasPrefix(part, "LocationConstraint=") {
-			locConstraint := strings.TrimPrefix(part, "LocationConstraint=")
+		if after, ok := strings.CutPrefix(part, "LocationConstraint="); ok {
+			locConstraint := after
 			config.LocationConstraint = &locConstraint
-		} else if strings.HasPrefix(part, "Tags=") {
-			tags, err := parseTagging(strings.TrimPrefix(part, "Tags="))
+		} else if after, ok := strings.CutPrefix(part, "Tags="); ok {
+			tags, err := parseTagging(after)
 			if err != nil {
 				return nil, err
 			}

cmd/versitygw/gateway_test.go

@@ -68,8 +68,7 @@ func initPosix(ctx context.Context) {
 		log.Fatalf("init posix: %v", err)
 	}
 
-	wg.Add(1)
-	go func() {
+	wg.Go(func() {
 		err = runGateway(ctx, be)
 		if err != nil && err != context.Canceled {
 			log.Fatalf("run gateway: %v", err)
@@ -79,8 +78,7 @@ func initPosix(ctx context.Context) {
 		if err != nil {
 			log.Fatalf("remove temp directory: %v", err)
 		}
-		wg.Done()
-	}()
+	})
 
 	// wait for server to start
 	time.Sleep(1 * time.Second)