Go group repository does not merge properly versions for the "list" endpoint

Steps to reproduce

• Create go-hosted
• Upload to the go-hosted 
  package = github.com/dgraph-io/badger
  version = v1.5.0
• Create go-proxy
  remote = https://gonexus.dev/
• Create a go-group with go-hosted and go-proxy as group members
• Try to get all available versions of the dgraph-io

• http://localhost:8081/repository/go-group/github.com/dgraph-io/badger/@v/list

Actual:

The result contains only hosted versions -> v1.5.0

"List" endpoint returns not empty data from the first member

Expected:

"List" endpoint returns all available versions of the package

• Try to install the latest version of the dgraph-io
•  At the moment the latest version that is available in the go-proxy = v1.6.2

• go get github.com/dgraph-io/badger/@latest

Actual:

Installed v1.5.0

Expected:

v1.6.2

For developers. Go group list endpoint has to get all available versions from the members, merge them, and return back