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>

plugin/plugin.go

@@ -42,10 +42,7 @@ var (
 
 // IsSkipPlugin returns true if the error is skipping the plugin
 func IsSkipPlugin(err error) bool {
-	if errors.Cause(err) == ErrSkipPlugin {
-		return true
-	}
-	return false
+	return errors.Cause(err) == ErrSkipPlugin
 }
 
 // Type is the type of the plugin