Use literal true/false values instead of GetBoolean() call

Co-authored-by: eiriktsarpalis <2813363+eiriktsarpalis@users.noreply.github.com>

Author: Copilot

src/ModelContextProtocol.Core/Protocol/ElicitRequestParams.cs

@@ -165,8 +165,10 @@ public class Converter : JsonConverter<PrimitiveSchemaDefinition>
                             switch (reader.TokenType)
                             {
                                 case JsonTokenType.True:
+                                    defaultBool = true;
+                                    break;
                                 case JsonTokenType.False:
-                                    defaultBool = reader.GetBoolean();
+                                    defaultBool = false;
                                     break;
                                 case JsonTokenType.Number:
                                     defaultNumber = reader.GetDouble();