Update DB dictionary to reflect renamed model

https://gitlab.com/gitlab-org/gitlab/-/merge_requests/122872#note_1446440006

Update DB dictionary to reflect renamed model
c90fa468 · Krasimir Angelov · 6324dca6 · c90fa468
--- a/db/docs/external_pull_requests.yml
+++ b/db/docs/external_pull_requests.yml
@@ -2,7 +2,6 @@
 table_name: external_pull_requests
 classes:
 - Ci::ExternalPullRequest
- ExternalPullRequest
 feature_categories:
 - continuous_integration
 description: TODO