Add workflow

Signed-off-by: Leo Lou <louyuhong@gmail.com>

Author: l4u

.github/workflows/build.yml

@@ -0,0 +1,6 @@
+name: Build ZMK firmware
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  build:
+    uses: zmkfirmware/zmk/.github/workflows/build-user-config.yml@v0.3