Added firmware build target

.forgejo/workflows/build.yml

@@ -1,6 +1,6 @@
 on: push
 jobs:
-  build-linux:
+  build-firmware:
     runs-on: docker
     container:
       image: forgejo.zenerdio.de/sebastian/cheapsdo-ci:v0.1.0
@@ -16,6 +16,23 @@ jobs:
             target/      
           key: build-cheapsdo
           restore-keys: audit-cheapsdo
+      - run: cd firmware && CARGO_HOME=~/.cargo cargo build --target thumbv7m-none-eabi --release
+
+  build-linux:
+    runs-on: docker
+    container:
+      image: forgejo.zenerdio.de/sebastian/cheapsdo-ci:v0.1.0
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/cache@v3
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/      
+          key: build-cheapsdo
       - run: cd hostsoftware && CARGO_HOME=~/.cargo cargo build --release
 
   build-windows: