Make 19.5.4 the latest model B firmware version

Author: sandeepmistry

src/WiFi101.h

@@ -21,7 +21,7 @@
 #define WIFI_H
 
 #define WIFI_FIRMWARE_LATEST_MODEL_A "19.4.4"
-#define WIFI_FIRMWARE_LATEST_MODEL_B "19.5.2"
+#define WIFI_FIRMWARE_LATEST_MODEL_B "19.5.4"
 
 // for backwards compatibility
 #define WIFI_FIRMWARE_REQUIRED WIFI_FIRMWARE_LATEST_MODEL_B