Update datafusion/optimizer/src/type_coercion.rs

Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

Author: liukun4515

datafusion/optimizer/src/type_coercion.rs

@@ -839,10 +839,7 @@ mod test {
 
         // concat
         {
-            let expr = Expr::ScalarFunction {
-                fun: Concat,
-                args: args.clone(),
-            };
+            let expr = concat(args.clone());
 
             let plan = LogicalPlan::Projection(Projection::try_new(
                 vec![expr],