Make publishPacket retain flag default to false

Author: Fapiko

Adafruit_MQTT.h

@@ -268,7 +268,8 @@ class Adafruit_MQTT {
   uint8_t connectPacket(uint8_t *packet);
   uint8_t disconnectPacket(uint8_t *packet);
   uint16_t publishPacket(uint8_t *packet, const char *topic, uint8_t *payload,
-                         uint16_t bLen, uint8_t qos, uint16_t maxPacketLen = 0);
+                         uint16_t bLen, uint8_t qos, uint16_t maxPacketLen = 0,
+                         bool retain = false);
   uint8_t subscribePacket(uint8_t *packet, const char *topic, uint8_t qos);
   uint8_t unsubscribePacket(uint8_t *packet, const char *topic);
   uint8_t pingPacket(uint8_t *packet);