Fix no_std compilation

Author: xitep

src/ast/mod.rs

@@ -11723,7 +11723,7 @@ pub enum OptimizerHintStyle {
 }
 
 impl fmt::Display for OptimizerHint {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match &self.style {
             OptimizerHintStyle::SingleLine { prefix } => {
                 f.write_str(prefix)?;