fix: linter issue

megacheck, gosimple and unused has been deprecated and subsumed by
staticcheck. And staticcheck also has been upgraded. we need to update
code for the linter issue.

close: #2945

Signed-off-by: Wei Fu <fuweid89@gmail.com>

pkg/testutil/helpers_unix.go

@@ -49,7 +49,7 @@ func RequiresRootM() {
 		fmt.Fprintln(os.Stderr, "skipping test that requires root")
 		os.Exit(0)
 	}
-	if 0 != os.Getuid() {
+	if os.Getuid() != 0 {
 		fmt.Fprintln(os.Stderr, "This test must be run as root.")
 		os.Exit(1)
 	}