feat(CI): add codecov

Author: kkweon

.github/workflows/go.yaml

@@ -19,8 +19,8 @@ jobs:
         with:
           go-version: 1.16
       - run: go build -v ./...
-      - run: go test -v ./...
-
+      - run: go test -race -coverprofile=coverage.txt -covermode=atomic -v ./...
+      - run: bash <(curl -s https://codecov.io/bash)
       - uses: go-semantic-release/action@v1.12.0
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}