Add support for go workspace

Thanks for stopping by to let us know something could be better!

**Is your feature request related to a problem? Please describe.**

When developing go modules in a monorepo, it would be nice to update versions transitively when changes happen in dependent libraries.

**Describe the solution you'd like**

`release-please` should parse a `go.work` file in the root folder in the same way that `cargo-workspace` or `node-workspace` works.

**Describe alternatives you've considered**

Did consider non-standard solutions but that is not as good.

**Additional context**

Will be opening a PR that implements this feature in a moment