increase StaticJsonBuffer to MQTT_MAX_SIZE

src/boiler.ino

@@ -411,7 +411,7 @@ void showInfo() {
 // CRC check is done to see if there are changes in the values since the last send to avoid too much wifi traffic
 void publishValues(bool force) {
     char                            s[20] = {0}; // for formatting strings
-    StaticJsonBuffer<512> jsonBuffer;
+    StaticJsonBuffer<MQTT_MAX_SIZE> jsonBuffer;
     char                            data[MQTT_MAX_SIZE] = {0};
     JsonObject &                    rootBoiler          = jsonBuffer.createObject();
     size_t                          rlen;