Incremented version to 2.13.1

Signed-off-by: GitHub <[email protected]>

build.gradle

@@ -7,7 +7,7 @@ import org.opensearch.gradle.test.RestIntegTestTask
 
 buildscript {
     ext {
-        opensearch_version = System.getProperty("opensearch.version", "2.13.0-SNAPSHOT")
+        opensearch_version = System.getProperty("opensearch.version", "2.13.1-SNAPSHOT")
         isSnapshot = "true" == System.getProperty("build.snapshot", "true")
         buildVersionQualifier = System.getProperty("build.version_qualifier", "")
         version_tokens = opensearch_version.tokenize('-')