Oops, I think I needed pull_request_target instead.

Change-Id: I58f3c5539fe94764d8922cf61d3e4ab53929460e
Reviewed-on: https://code-review.googlesource.com/c/re2/+/59694
Reviewed-by: Aaron Jacobs <jacobsa@google.com>
Reviewed-by: Paul Wankadia <junyer@google.com>

.github/workflows/pr.yml

diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index 9de006d..8ede73b 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -1,6 +1,6 @@
 name: PR
 on:
-  pull_request:
+  pull_request_target:
     branches: [main]
     types: [opened]
 jobs: