feat: add retest comment, delete it

src/lib/comments.mjs

@@ -0,0 +1,7 @@
+export async function createComment(repo, issueId, body) {
+  return repo.issues(issueId).comments.create({ body });
+}
+
+export async function deleteComment(repo, commentId) {
+  return repo.issues.comments(commentId).remove();
+}