Update version to 1.40.0-SNAPSHOT (#1460)

Author: opentelemetrybot

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+## Version 1.39.0 (2024-09-17)
+
 ### AWS X-Ray propagator
 
 - Handle too short `X-Amzn-Trace-Id` header

version.gradle.kts

@@ -1,5 +1,5 @@
-val stableVersion = "1.39.0-SNAPSHOT"
-val alphaVersion = "1.39.0-alpha-SNAPSHOT"
+val stableVersion = "1.40.0-SNAPSHOT"
+val alphaVersion = "1.40.0-alpha-SNAPSHOT"
 
 allprojects {
   if (findProperty("otel.stable") != "true") {