Update aws-lambda-java-events to 3.15.0

Author: gu-scala-steward-public-repos[bot]

build.sbt

@@ -351,7 +351,7 @@ lazy val sloMonitor = lambda("slomonitor", "slomonitor", Some("com.gu.notificati
     Seq(
       description := "Monitors SLO performance for breaking news notifications",
       libraryDependencies ++= Seq(
-        "com.amazonaws" % "aws-lambda-java-events" % "3.14.0",
+        "com.amazonaws" % "aws-lambda-java-events" % "3.15.0",
         "com.amazonaws" % "aws-java-sdk-cloudwatch" % awsSdkVersion,
         "io.netty" % "netty-codec" % nettyVersion,
         "io.netty" % "netty-codec-http" % nettyVersion,