docker pull jsii/superchain fails due to missing "latest" tag.

### Describe the bug

No "latest" tag for jsii/superchain, so docker pull jsii/superchain fails:

This also has implications for workflows set up by Projen, which tries to pickup the latest jsii/superchain image.
Workaround for now has been to manually update these workflows with an existing tag in Dockerhub.

### Expected Behavior

docker pull jsii/superchain

would succeed.

### Current Behavior

❯ docker pull jsii/superchain
Using default tag: latest
Error response from daemon: manifest for jsii/superchain:latest not found: manifest unknown: manifest unknown

### Reproduction Steps

Run "docker pull jsii/superchain"

### Possible Solution

_No response_

### Additional Information/Context

_No response_

### SDK version used

N/A

### Environment details (OS name and version, etc.)

macOS 12.3.1

Start by reproducing the failure with `docker pull jsii/superchain` and inspect how the jsii/superchain image is published to Docker Hub. Check the Projen workflows that consume the image; done means the `latest` tag exists, the pull succeeds, and those workflows no longer need a manually selected tag.

Written by the indexing model from the issue text.