Added prefer_const_constructors linter

Author: Bungeefan

analysis_options.yaml

@@ -2,3 +2,7 @@ include: package:lints/recommended.yaml
 
 # Additional information about this file can be found at
 # https://dart.dev/guides/language/analysis-options
+
+linter:
+  rules:
+    - prefer_const_constructors

lib/src/printers/simple_printer.dart

@@ -50,7 +50,7 @@ class SimplePrinter extends LogPrinter {
   String _stringifyMessage(dynamic message) {
     final finalMessage = message is Function ? message() : message;
     if (finalMessage is Map || finalMessage is Iterable) {
-      var encoder = JsonEncoder.withIndent(null);
+      var encoder = const JsonEncoder.withIndent(null);
       return encoder.convert(finalMessage);
     } else {
       return finalMessage.toString();