Fix data buffer overflow wrong length bytes

Sometimes receiving byte 6 or 7 is wrong and packet->length will be very high. There was no check that any more bytes could fit into the packet->data buffer. This could resulted in crashes or strange behavior.

Author: ArendJan

Adafruit_Fingerprint.cpp

@@ -559,6 +559,10 @@ Adafruit_Fingerprint::getStructuredPacket(Adafruit_Fingerprint_Packet *packet,
       break;
     }
     idx++;
+    if ((idx + 9) >= sizeof(packet->data))
+    {
+      return FINGERPRINT_BADPACKET;
+    }
   }
   // Shouldn't get here so...
   return FINGERPRINT_BADPACKET;