fix: add thumbv7em-none-eabihf target to release workflow

The embedded cross-compilation check requires the ARM Cortex-M target
to be installed. Added target installation to the rust-toolchain step.

Author: lxsaah

.github/workflows/release.yml

@@ -19,6 +19,8 @@ jobs:
 
     - name: Install Rust
       uses: dtolnay/rust-toolchain@stable
+      with:
+        targets: thumbv7em-none-eabihf
 
     - name: Cache dependencies
       uses: actions/cache@v3