chore: close stale issues bot uses outdated props (aws#21818)

https://github.com/aws-actions/stale-issue-cleanup `exempt-xxx-label` was changed to `exempt-xxx-labels` between versions, we bumped this action to v5 back in april but no errors were ever thrown for this

----

### All Submissions:

* [ ] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md)

### Adding new Unconventional Dependencies:

* [ ] This PR adds new unconventional dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md/#adding-new-unconventional-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/main/INTEGRATION_TESTS.md)?
	* [ ] Did you use `yarn integ` to deploy the infrastructure and generate the snapshot (i.e. `yarn integ` without `--dry-run`)?

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

.github/workflows/close-stale-issues.yml

@@ -25,9 +25,9 @@ jobs:
 
         # These labels are required
         stale-issue-label: closing-soon
-        exempt-issue-label: no-autoclose
+        exempt-issue-labels: no-autoclose
         stale-pr-label: closing-soon
-        exempt-pr-label: no-autoclose
+        exempt-pr-labels: no-autoclose
         response-requested-label: response-requested
 
         # Don't set closed-for-staleness label to skip closing very old issues