Fix publishing-api ref

- deployed-to-production has vanished, and publishing-api is
  on ci, so main and deployed-to-production are effectively the
  same.

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
   dependency-review:
     name: Dependency Review scan
     uses: alphagov/govuk-infrastructure/.github/workflows/dependency-review.yml@main
-  
+
   security-analysis:
     name: Security Analysis
     uses: alphagov/govuk-infrastructure/.github/workflows/brakeman.yml@main
@@ -67,7 +67,6 @@ jobs:
         uses: actions/checkout@v3
         with:
           repository: alphagov/publishing-api
-          ref: deployed-to-production
           path: vendor/publishing-api
 
       - name: Setup Ruby