Update platformio.ini

Author: Jason2866

examples/espidf-arduino-matter-light/platformio.ini

@@ -17,8 +17,11 @@ platform = espressif32
 framework = arduino, espidf
 board_build.partitions = partitions.csv
 monitor_speed = 115200
-build_unflags = -std=c++17
-build_flags = -std=gnu++2a
+build_unflags = 
+    -std=c++17
+    -std=gnu++2b
+build_flags =
+    -std=gnu++2a
 
 [env:esp32c6]
 board = esp32-c6-devkitc-1