Run 'go vet' in github action

Author: lauripiispanen

.github/workflows/go.yml

@@ -18,6 +18,9 @@ jobs:
       with:
         go-version: 1.15
 
+    - name: Vet
+      run: go vet -v ./...
+
     - name: Build
       run: go build -v ./...