Serve "observed at" times for Go modules

"Published" is empty for GO package versions on the website https://deps.dev/go/github.com%2Frs%2Fzerolog/v1.31.0/versions :

Same for the REST API:
NPM: https://api.deps.dev/v3alpha/systems/npm/packages/typescript

GO: https://api.deps.dev/v3alpha/systems/go/packages/github.com%2Frs%2Fzerolog

I checked all systems and GO and NUGET seem to be incomplete? The REST API documentation does not mention why some attributes are missing in these systems.

#### available: versions + published_at + dependents
CARGO https://deps.dev/cargo/rand/0.8.5/versions
NPM https://deps.dev/npm/react/18.2.0/versions
PYPI https://deps.dev/pypi/beautifulsoup4/4.12.2/versions
MAVEN https://deps.dev/maven/org.springframework%3Aspring-core/6.1.1/versions
#### available: versions + dependents
GO https://deps.dev/go/github.com%2Frs%2Fzerolog/v1.31.0/versions
#### available: versions + published_at
NUGET https://deps.dev/nuget/hangfire.core/1.8.6

### Is it possible to add the published timestamp?
The underlying source https://index.golang.org/index has timestamp so I am wondering why that aren't available on deps.dev. I need this information to be available in my project to be able to build package timelines.