If you have trouble downloading the dependencies, e.g. golang.org/x/sys shown by go get -u, please try

user@~> mkdir -p $GOPATH/src/golang.org/x/
user@~> cd $GOPATH/src/golang.org/x/
user@~> git clone https://github.com/golang/sys.git

, then specify local dependency of golang.org/x/sys in go.mod and rebuild the project.

Keep using go-isatty v0.0.3 in go.mod if you don't want any trouble circumventing the GFW.