Update dependency org.opensearch.client:opensearch-rest-client to v2.18.0

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

api/build.gradle

@@ -51,7 +51,7 @@ dependencies {
     implementation 'com.graphql-java:graphql-java:20.9'
     implementation 'com.graphql-java-kickstart:graphql-java-servlet:12.0.0'
 
-    implementation 'org.opensearch.client:opensearch-rest-client:2.17.1'
+    implementation 'org.opensearch.client:opensearch-rest-client:2.18.0'
     implementation 'org.opensearch.client:opensearch-java:2.16.0'
 
     testImplementation "io.dropwizard:dropwizard-testing:${dropwizardVersion}"