[nbgitpuller] Add beta release to a community hub image and monitor

[jnywong]

Context

For #7575 , we should deploy nbgitpuller v1.3.0b into a community hub image that actively uses the feature so that we can validate there are no major bugs before making proper minor release

Definition of Done

• Identify a good candidate community that actively uses nbgitpuller
• Deploy beta version
• Monitor and review nbgitpuller usage with both quantitative and qualitative feedback

[jnywong]

Note to future self: a useful GCP query to monitor nbgitpuller logs

resource.type="k8s_container"
resource.labels.cluster_name="cb-cluster"
resource.labels.container_name="notebook"
textPayload=~"returned non-zero exit status 128"

[jnywong]

Took a look at the GCP logs for the Cloudbank hubs and saw a bunch of errors recently presumably from recent GH instability. I think it would be nice to monitor the beta release with this cluster! Sent an email to the community to propose such an idea and I opened a PR to bump to the beta nbgp version for the cal-icor/base-user-image cal-icor/base-user-image#120.

[jnywong]

The PR was merged! Now to coordinate with the community for a small targeted deployment for testing and monitoring.