ci: ignore failed PR lookups when bumping ocv

Author: github-actions[bot]

.github/workflows/sync-upstream.yml

@@ -54,9 +54,10 @@ jobs:
           git fetch origin ocv:refs/remotes/origin/ocv
           scan_ref=$(git rev-parse --verify --quiet origin/ocv >/dev/null && printf origin/ocv || printf HEAD)
           git log --first-parent --reverse --format='%H' "$previous..$scan_ref" | while read -r sha; do
-            pull_requests=$(gh api "repos/${{ github.repository }}/commits/$sha/pulls" -q '.[] | select(.base.ref == "ocv") | "#\(.number) \(.title)"' 2>/dev/null || true)
-            if [ -n "$pull_requests" ]; then
-              printf '%s\n' "$pull_requests"
+            if pull_requests=$(gh api "repos/${{ github.repository }}/commits/$sha/pulls" -q '.[] | select(.base.ref == "ocv") | "#\(.number) \(.title)"' 2>/dev/null); then
+              if [ -n "$pull_requests" ]; then
+                printf '%s\n' "$pull_requests"
+              fi
             fi
           done | awk '!seen[$1]++' > "$prs"