gitstream pr context variable doesn't contain all pr checks

[dorongutman]

Describe the bug

In my PR there are checks showing the status of external CI systems runs, like the docker build, or whether tests passed or failed.
However, when I iterate over pr.checks in gitstream these statuses don't show.

To Reproduce

See full repro in dorongutman/reproduce-gitstream-main#2

I manually created a status check with:

curl -X POST \
  -H "Authorization: token $GITHUB_TOKEN" \
  -H "Accept: application/vnd.github.v3+json" \
  https://api.github.com/repos/dorongutman/reproduce-gitstream-main/statuses/e87a06aa1a29e94e89876248dd1e644fc6aadba8 \
  -d '{
    "state": "success",
    "target_url": "https://example.com",
    "description": "External check running",
    "context": "my-external-service"
  }'

and I used this gitstream.cm file to dump the contents of pr.checks (I tried the entire pr object and also the entire variable contexts in the playground - same thing):

# -*- mode: yaml -*-

manifest:
  version: 1.0
automations:
  dump_checks:
    on:
      - comment_added
    if:
      - true
    run:
      - action: add-comment@v1
        args:
          comment: |
            CHECKS DUMP:
            ```yaml
            {{ pr.checks | dump(2) | indent(12) | safe }}
            ```

Expected behavior

I expect to have all of the checks in pr.checks so I could approve the gitstream check upon successful build and/or tests passing.