Fix linting issues (#595)

* fix lint

* Bump golangci-lint action to v8 and update linting args

* fix lint errors

* fix: correct loop condition in main function to process remaining arguments

plugin/yaml/yaml.go

@@ -67,7 +67,7 @@ func (l *listOrString) UnmarshalYAML(value *yaml.Node) error {
 		l.Str = str
 		return nil
 	}
-	return fmt.Errorf("Failed to unmarshal OneOfType")
+	return fmt.Errorf("failed to unmarshal OneOfType")
 }
 
 type yamlPipe struct {