fix(ci): pass issue_number when labeling new issues

context.issue spreads to { owner, repo, number }, but Octokit v9 requires
issue_number. The request hit /repos/.../issues//labels and returned 404,
so no opened issue was ever labeled.

.github/workflows/label-issues.yml

@@ -26,5 +26,9 @@ jobs:
             const labels = getIssueLabels(context.payload.issue.body ?? "");
 
             if (labels.length > 0) {
-              await github.rest.issues.addLabels({ ...context.issue, labels });
+              await github.rest.issues.addLabels({
+                ...context.repo,
+                issue_number: context.issue.number,
+                labels,
+              });
             }