add github action to automatically build the code on push

.github/workflows/build.yml

@@ -0,0 +1,14 @@
+name: Build
+on: [push]
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-18.04
+    steps:
+      - name: Set up Go 1.12
+        uses: actions/setup-go@v1
+        with:
+          go-version: 1.12
+        id: go
+      - name: Build
+        run: make