Update goenv URLs

I am the owner of https://github.com/go-nv/goenv

We will be migrating from v2 (shell based CLI) to v3 (go-based CLI)

`master` branch will no longer be the default and move to `main`.

`master` is the legacy v2 model and `main` is v3 - a fully go-based CLI. We will need some time to migrate these images to use the compiled binaries instead and add support for all platforms/archs.

We plan to keep support until EoY 2028. This will give us plenty of time to test and migrate everything safely and correctly

**The benefits:**

Go based CLI provides instant ability to download any binary without waiting for PR to update installables

More secure, less obtrusive to a user's shell.

We will need some time to fully migrate all the container images to use the binaries. But this is a start

Search the repository's Dockerfiles and related image definitions for goenv URLs and references to the master branch. Compare each reference with the stated v2/master and v3/main migration, then verify that all in-scope images point to the intended branch or source without changing legacy support unexpectedly.

Written by the indexing model from the issue text.