0.4.0

• breaking change: drop org.elasticsearch.client.RestHighLevelClient and replace with org.elasticsearch.client.RestClient (LowLevelClient). This will drop the big transitive dependency org.elasticsearch:elasticsearch and opens compatibility to Elasticsearch 8 and OpenSearch.
• version updates (spring-boot 2.6.6)
• added spring boot 2.5 and 2.6 compatibility tests
• added java 17 and 18 compatibility tests
• added Elasticsearch 8.1, 8.0, 7.17, 7.16, 7.15, 7.14 and 7.13 compatibility tests
• added Opensearch 1.0, 1.1, 1.2 and 1.3 compatibility tests
• fixed issue #114