[AUTO] Increment version to 1.3.15-SNAPSHOT (#937)

* Increment version to 1.3.15-SNAPSHOT

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

* push again

Signed-off-by: Peter Zhu <zhujiaxi@amazon.com>

---------

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

build.gradle

@@ -10,7 +10,7 @@ import org.opensearch.gradle.testclusters.StandaloneRestIntegTestTask
 buildscript {
     ext {
         opensearch_group = "org.opensearch"
-        opensearch_version = System.getProperty("opensearch.version", "1.3.14-SNAPSHOT")
+        opensearch_version = System.getProperty("opensearch.version", "1.3.15-SNAPSHOT")
         // 1.0.0 -> 1.0.0.0, and 1.0.0-SNAPSHOT -> 1.0.0.0-SNAPSHOT
         opensearch_build = opensearch_version.replaceAll(/(\.\d+)([^\d]*)$/, '$1.0$2')
         common_utils_version = System.getProperty("common_utils.version", opensearch_build)