build: correct the module path

[yin1999]

For a published module, we should use repo's url as the module path, so we can download or refer it by go module.

And for we are in v4.x, so we should add the /v4 suffix to the module path.

Reference

https://go.dev/doc/tutorial/create-module#start:

Run the go mod init command, giving it your module path -- here, use example.com/greetings. If you publish a module, this must be a path from which your module can be downloaded by Go tools. That would be your code's repository.

[jeessy2]

thanks