Update Elasticsearch version

Author: xuanxu

.github/workflows/tests.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Install Elasticsearch
         uses: ankane/setup-elasticsearch@v1
         with:
-          elasticsearch-version: 7.12.0
+          elasticsearch-version: 9
       - name: Verify Elasticsearch connection and create index
         env:
           ELASTICSEARCH_URL: http://localhost:9200