Static cast size in additon

Signed-off-by: Sara Damiano <sdamiano@stroudcenter.org>

.github/ISSUE_TEMPLATE.md

@@ -22,7 +22,7 @@ with your board before submitting any issues.
 
 Main processor board: <!-- Uno, Zero, ESP32, Particle, etc -->
 Modem: <!-- Brand, model, variant, firmware version -->
-TinyGSM version: <!-- always try to use the latest (0.10.5) -->
+TinyGSM version: <!-- always try to use the latest (0.10.6) -->
 Code: <!-- Example name or paste in your code -->
 
 ### Scenario, steps to reproduce

library.json

@@ -1,6 +1,6 @@
 {
   "name": "TinyGSM",
-  "version": "0.10.5",
+  "version": "0.10.6",
   "description": "A small Arduino library for GPRS modules, that just works. Includes examples for Blynk, MQTT, File Download, and Web Client. Supports many GSM, LTE, and WiFi modules with AT command interfaces.",
   "keywords": "GSM, AT commands, AT, SIM800, SIM900, A6, A7, M590, ESP8266, SIM7000, SIM800A, SIM800C, SIM800L, SIM800H, SIM808, SIM868, SIM900A, SIM900D, SIM908, SIM968, M95, MC60, MC60E, BG96, ublox, Quectel, SIMCOM, AI Thinker, LTE, LTE-M",
   "authors":

library.properties

@@ -1,5 +1,5 @@
 name=TinyGSM
-version=0.10.5
+version=0.10.6
 author=Volodymyr Shymanskyy
 maintainer=Volodymyr Shymanskyy
 sentence=A small Arduino library for GPRS modules, that just works.

src/TinyGsmCommon.h

@@ -10,7 +10,7 @@
 #define SRC_TINYGSMCOMMON_H_
 
 // The current library version number
-#define TINYGSM_VERSION "0.10.5"
+#define TINYGSM_VERSION "0.10.6"
 
 #if defined(SPARK) || defined(PARTICLE)
 #include "Particle.h"

src/TinyGsmTCP.tpp

@@ -133,7 +133,7 @@ class TinyGsmTCP {
       // Returns the combined number of characters available in the TinyGSM
       // fifo and the modem chips internal fifo.
       if (!rx.size()) { at->maintain(); }
-      return rx.size() + sock_available;
+      return static_cast<uint16_t>(rx.size()) + sock_available;
 
 #elif defined TINY_GSM_BUFFER_READ_AND_CHECK_SIZE
       // Returns the combined number of characters available in the TinyGSM
@@ -146,7 +146,7 @@ class TinyGsmTCP {
         }
         at->maintain();
       }
-      return rx.size() + sock_available;
+      return static_cast<uint16_t>(rx.size()) + sock_available;
 
 #else
 #error Modem client has been incorrectly created