ci: don't pin the arm toolchain version

We don't pin risc-v, and if new compilers break things, it would
be good to know about it...

Author: ppannuto

.github/workflows/ci.yml

@@ -38,8 +38,7 @@ jobs:
         with:
           submodules: recursive
       - uses: carlosperate/arm-none-eabi-gcc-action@v1
-        with:
-          release: '10.3-2021.07' # The arm-none-eabi-gcc release to use.
+      - run: arm-none-eabi-gcc --version
       - name: setup-riscv-toolchain
         run: sudo apt-get install -y gcc-riscv64-unknown-elf
       - name: ci-build