Run build checks on PRs targeting master branch (#922)

.github/workflows/build.yml

@@ -0,0 +1,23 @@
+name: build
+
+on: 
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+
+    - name: Checkout repo
+      uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+
+    - name: Set up Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: ^1.15
+
+    - name: Build binaries
+      run: go run build/build.go