Limit mergeable_state refreshing

Author: Sakib25800

src/bors/handlers/refresh.rs

@@ -72,7 +72,9 @@ async fn refresh_unknown_mergeable_prs(
         .await?;
     tracing::debug!("Found {} PRs with unknown mergeable state", prs.len());
 
-    for pr in prs {
+    // Process limited number of PRs per refresh cycle to avoid rate limiting.
+    // GH Enterprise rate limit = 164 requests per 2 minutes.
+    for pr in prs.iter().take(100) {
         tracing::debug!("Refreshing mergeable state for PR {}", pr.number);
         match repo.client.get_pull_request(pr.number).await {
             Ok(pr) => {