Do not lock the toolchain to a version

Attempting to lock the toolchain to a version seems to cause
issues, especially in the case of Linux. Letting the PlatformIO
do the toolchain package selection.

platformio.ini

@@ -129,7 +129,6 @@ build_flags =
 platform = https://github.com/maxgerhardt/platform-raspberrypi.git
 platform_packages =
     framework-arduinopico@https://github.com/rabbitholecomputing/arduino-pico.git#v3.6.0-DaynaPORT
-    toolchain-rp2040-earlephilhower@https://github.com/earlephilhower/pico-quick-toolchain/releases/download/2.1.0-a/x86_64-w64-mingw32.arm-none-eabi-d3d2e6b.230911-v2.zip
 framework = arduino
 board = rpipicow
 board_build.core = earlephilhower