Migrate from deprecated dep tool to go modules

[arwineap]

Dep was an official experiment to implement a package manager for Go. As of 2020, Dep is deprecated and archived in favor of Go modules, which have had official support since Go 1.11.

The dep maintainers have deprecated their dep tool in favor of go modules.

Would you accept a PR to migrate to go modules?

Would you prefer to keep the libraries vendored?