Update Arduino core in PIO (#2018)

code/platformio.ini

@@ -23,14 +23,15 @@ arduino_core_2_4_1 = espressif8266@1.7.3
 arduino_core_2_4_2 = espressif8266@1.8.0
 arduino_core_2_5_0 = espressif8266@2.0.4
 arduino_core_2_5_1 = espressif8266@2.1.1
-arduino_core_2_5_2 = espressif8266@2.2.2
+arduino_core_2_5_2 = espressif8266@2.2.3
+arduino_core_2_6_1 = espressif8266@2.3.0
 
 # Development platforms
 arduino_core_develop = https://github.com/platformio/platform-espressif8266#develop
 arduino_core_git = https://github.com/platformio/platform-espressif8266#feature/stage
 
 platform = ${common.arduino_core_2_3_0}
-platform_latest = ${common.arduino_core_2_5_2}
+platform_latest = ${common.arduino_core_2_6_1}
 
 # ------------------------------------------------------------------------------
 # FLAGS: DEBUG