Use `go install` in make setup instead of `go get`

[bsushmith]

Summary
Use go install in make setup instead of go get.

https://tip.golang.org/doc/go1.16#modules

go install, with or without a version suffix (as described above), is now the recommended way to build and install packages in module mode. go get should be used with the -d flag to adjust the current module's dependencies without building packages, and use of go get to build and install packages is deprecated. In a future release, the -d flag will always be enabled.