Revert "Fix label assignment by using context.issue instead of context.repo"

This reverts commit dab8886.

Author: TravisEz13

.github/workflows/backport.yml

@@ -31,7 +31,8 @@ jobs:
 
               // Add the label to the issue
               await github.rest.issues.addLabels({
-                ...context.issue,
+                ...context.repo,
+                issue_number: context.issue.number,
                 labels: [label],
               });
             } else {