Please update FreeRTOS to the latest version

[bojczmac]

When I enable link time optimization (-flto) I get a linker error regarding vTaskSwitchContext():

arm-none-eabi/bin/ld: /tmp/ccP992vo.ltrans0.ltrans.o: in function `PendSV_Handler':
<artificial>:(.text.PendSV_Handler+0x1c): undefined reference to `vTaskSwitchContext'

This issue was fixed in the latest version of the FreeRTOS so please update.