chore: bump snapshot version to 1.5.16-SNAPSHOT

Author: aws-sdk-kotlin-ci

gradle.properties

@@ -6,7 +6,7 @@ kotlin.native.ignoreDisabledTargets=true
 org.gradle.jvmargs=-Xmx10g -XX:MaxMetaspaceSize=2G
 
 # sdk
-sdkVersion=1.5.15
+sdkVersion=1.5.16-SNAPSHOT
 
 # dokka config (values specified at build-time as needed)
 smithyKotlinDocBaseUrl=https://sdk.amazonaws.com/kotlin/api/smithy-kotlin/api/$smithyKotlinRuntimeVersion/