build: use frozen lock file

Signed-off-by: Berend Sliedrecht <blu3beri@proton.me>

.github/workflows/build.yml

@@ -423,7 +423,7 @@ jobs:
       - name: Build
         run: |
           cargo install --bins --git https://github.com/rust-embedded/cross --tag v${{ env.CROSS_VERSION }} cross
-          cross build --lib --release --target ${{matrix.target}} --locked
+          cross build --lib --release --target ${{matrix.target}} --locked --frozen
 
       - name: Upload artifacts
         uses: actions/upload-artifact@v3