Allow CI failure as evidence for 'external' bucket

Renovate-style PRs whose CI breaks because of an upstream tool release legitimately belong in 'external'. The previous wording forbade CI failure as a signal for both author and external; loosen to forbid only the author shift.

Author: trask

.github/scripts/pull-request-dashboard.py

@@ -52,7 +52,7 @@
 Merge-conflict status is shown in a separate deterministic column of the \
 dashboard — do not infer it. CI is summarized as a single boolean \
 (failing yes/no); pending checks are treated as not-failing. CI failure \
-on its own is NOT a reason to assign the PR to the author or to external: \
+on its own is NOT a reason to assign the PR to the author: \
 PRs can still be reviewed and approved while CI is failing. Treat CI \
 status only as weak supporting evidence and focus on the conversation \
 (comments, reviews, commits).