Added thumbv8m + riscv32imac targets to QA pipeline #61

Job	Run time
Linting	10s
Check documentation	22s
Check code style	13s
Build no_std targets (thumbv6m-none-eabi, stable)	15s
Build no_std targets (thumbv6m-none-eabi, beta)	14s
Tests (ubuntu-latest, stable)	23s
Build no_std targets (thumbv6m-none-eabi, nightly)	26s
Tests (ubuntu-latest, beta)	17s
Build no_std targets (thumbv7m-none-eabi, stable)	22s
Tests (ubuntu-latest, nightly)	18s
Build no_std targets (thumbv7m-none-eabi, beta)	22s
Build no_std targets (thumbv7m-none-eabi, nightly)	13s
Build no_std targets (thumbv8m.main-none-eabihf, stable)	22s
Build no_std targets (thumbv8m.main-none-eabihf, beta)	23s
Build no_std targets (thumbv8m.main-none-eabihf, nightly)	26s
Build no_std targets (riscv32imac-unknown-none-elf, stable)	15s
Build no_std targets (riscv32imac-unknown-none-elf, beta)	22s
Build no_std targets (riscv32imac-unknown-none-elf, nightly)	25s
	5m 48s

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