build: add coverage report to ci script

.github/workflows/go.yml

@@ -26,5 +26,12 @@ jobs:
       run: |
         go get -v -t -d ./...
 
-    - name: Build
-      run: go test
+    - name: Generate coverage report
+      run: go test -race -coverprofile=coverage.txt -covermode=atomic
+    
+    - name: Upload coverage to Codecov  
+      uses: codecov/codecov-action@v1
+      with:
+        file: ./coverage.txt
+        name: codecov-umbrella
+        fail_ci_if_error: true