Correct SARA_R5_COMMAND_IMEI

Author: PaulZC

src/SparkFun_u-blox_SARA-R5_Arduino_Library.h

@@ -98,7 +98,7 @@ const char SARA_R5_COMMAND_MANU_ID[] = "+CGMI";   // Manufacturer identification
 const char SARA_R5_COMMAND_MODEL_ID[] = "+CGMM";  // Model identification
 const char SARA_R5_COMMAND_FW_VER_ID[] = "+CGMR"; // Firmware version identification
 const char SARA_R5_COMMAND_SERIAL_NO[] = "+CGSN"; // Product serial number
-const char SARA_R5_COMMAND_IMEI[] = "+CSN";       // IMEI identification
+const char SARA_R5_COMMAND_IMEI[] = "+GSN";       // IMEI identification
 const char SARA_R5_COMMAND_IMSI[] = "+CIMI";      // IMSI identification
 const char SARA_R5_COMMAND_CCID[] = "+CCID";      // SIM CCID
 const char SARA_R5_COMMAND_REQ_CAP[] = "+GCAP";   // Request capabilities list