Update TinyGsmClientSIM800.h

Question mark not a valid mode for this at command AT+CBC

src/TinyGsmClientSIM800.h

@@ -698,7 +698,7 @@ TINY_GSM_MODEM_WAIT_FOR_NETWORK()
   }
 
   uint8_t getBattChargeState() {
-    sendAT(GF("+CBC?"));
+    sendAT(GF("+CBC"));
     if (waitResponse(GF(GSM_NL "+CBC:")) != 1) {
       return false;
     }
@@ -710,7 +710,7 @@ TINY_GSM_MODEM_WAIT_FOR_NETWORK()
   }
 
   bool getBattStats(uint8_t &chargeState, int8_t &percent, uint16_t &milliVolts) {
-    sendAT(GF("+CBC?"));
+    sendAT(GF("+CBC"));
     if (waitResponse(GF(GSM_NL "+CBC:")) != 1) {
       return false;
     }