Update README.md

Author: earlephilhower

README.md

@@ -4,7 +4,7 @@
 
 Raspberry Pi Pico Arduino core, for all RP2040 boards
 
-This is a port of the RP2040 (Raspberry Pi Pico processor) to the Arduino ecosystem. It uses the bare Raspberry Pi Pico SDK and a custom GCC 10.3/Newlib 4.0 toolchain.
+This is a port of the RP2040 (Raspberry Pi Pico processor) to the Arduino ecosystem. It uses the bare Raspberry Pi Pico SDK and a custom GCC 12.3/Newlib 4.0 toolchain.
 
 # Documentation
 See https://arduino-pico.readthedocs.io/en/latest/ along with the examples for more detailed usage information.