Update to latest CRT to bring in several payload fixes (#190)

Author: bretambrose

sdk/pom.xml

@@ -42,7 +42,7 @@
     <dependency>
       <groupId>software.amazon.awssdk.crt</groupId>
       <artifactId>aws-crt</artifactId>
-      <version>0.15.8</version>
+      <version>0.15.9</version>
     </dependency>
     <dependency>
       <groupId>junit</groupId>