Update build_and_test.yml

Try to build crate for thumb6m-none-eabi target architecture.

Author: jhodapp

.github/workflows/build_and_test.yml

@@ -16,6 +16,13 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
+    - name: Install latest rust toolchain
+      uses: actions-rs/toolchain@v1
+      with:
+        toolchain: stable
+        target: thumbv6m-none-eabi
+        default: true
+        override: true
     - name: Build crate
       run: cargo build --verbose
     - name: Build debug examples