Increment version to 1.3.6-SNAPSHOT (#506)

Signed-off-by: opensearch-ci-bot <opensearch-infra@amazon.com>

Signed-off-by: opensearch-ci-bot <opensearch-infra@amazon.com>
Co-authored-by: opensearch-ci-bot <opensearch-infra@amazon.com>

Author: opensearch-trigger-bot[bot]

build.gradle

@@ -13,7 +13,7 @@ import java.util.function.Predicate
 
 buildscript {
     ext {
-        opensearch_version = System.getProperty("opensearch.version", "1.3.5-SNAPSHOT")
+        opensearch_version = System.getProperty("opensearch.version", "1.3.6-SNAPSHOT")
         // 1.1.0 -> 1.1.0.0, and 1.1.0-SNAPSHOT -> 1.1.0.0-SNAPSHOT
         opensearch_build = opensearch_version.replaceAll(/(\.\d)([^\d]*)$/, '$1.0$2')
         notification_version = System.getProperty("notification.version", opensearch_build)