use codecov action v1 (#985)

.github/workflows/go.yml

@@ -29,4 +29,4 @@ jobs:
       run: go test -race -coverprofile=coverage.txt -covermode=atomic ./...
 
     - name: Codecov
-      uses: codecov/codecov-action@v2
+      uses: codecov/codecov-action@v1