BCR reviewer: skip draft PRs (#1929)

Addressing
https://github.com/bazelbuild/bazel-central-registry/pull/1658#issuecomment-2010947718

Tested at
https://github.com/meteorcloudy/bazel-central-registry/actions/runs/8390212422/job/22978131199
diff --git a/actions/bcr-pr-reviewer/index.js b/actions/bcr-pr-reviewer/index.js
index d468c2a..4339356 100644
--- a/actions/bcr-pr-reviewer/index.js
+++ b/actions/bcr-pr-reviewer/index.js
@@ -222,10 +222,21 @@
 }
 
 async function reviewPR(octokit, owner, repo, prNumber) {
-
   console.log('\n');
   console.log(`Processing PR #${prNumber}`);
 
+  // Skip if the PR is a draft
+  const prInfo = await octokit.rest.pulls.get({
+    owner,
+    repo,
+    pull_number: prNumber,
+  });
+
+  if (prInfo.data.draft) {
+    console.log('Skipping draft PR');
+    return;
+  }
+
   // Fetch modified modules
   const modifiedModules = await fetchAllModifiedModules(octokit, owner, repo, prNumber);
   console.log(`Modified modules: ${Array.from(modifiedModules).join(', ')}`);