version bump: 3.8.0 (#866)

Signed-off-by: Simeon Widdis <sawiddis@amazon.com>

Author: Swiddis

build.gradle

@@ -9,7 +9,7 @@ import java.util.concurrent.Callable
 
 buildscript {
     ext {
-        opensearch_version = System.getProperty("opensearch.version", "3.7.0-SNAPSHOT")
+        opensearch_version = System.getProperty("opensearch.version", "3.8.0-SNAPSHOT")
         buildVersionQualifier = System.getProperty("build.version_qualifier", "")
         isSnapshot = "true" == System.getProperty("build.snapshot", "true")
         // 2.2.0-SNAPSHOT -> 2.2.0.0-SNAPSHOT