pick an embedded target with atomics

Author: KodrAus

.github/workflows/rust.yml

@@ -54,7 +54,7 @@ jobs:
       - name: Install Rust toolchain
         run: |
           rustup default nightly
-          rustup target add thumbv6m-none-eabi
+          rustup target add thumbv7em-none-eabi
 
       - name: Default features
-        run: cargo build -Z avoid-dev-deps --features spin_no_std --target thumbv6m-none-eabi
+        run: cargo build -Z avoid-dev-deps --features spin_no_std --target thumbv7em-none-eabi