Bump default agent image versions

Author: chadlwilson

src/main/java/cd/go/contrib/elasticagent/KubernetesInstanceFactory.java

@@ -300,8 +300,8 @@ private static Map<String, String> getJinJavaContext() {
         HashMap<String, String> context = new HashMap<>();
         context.put(POD_POSTFIX, UUID.randomUUID().toString());
         context.put(CONTAINER_POSTFIX, UUID.randomUUID().toString());
-        context.put(GOCD_AGENT_IMAGE, "gocd/gocd-agent-alpine-3.17");
-        context.put(LATEST_VERSION, "v23.1.0");
+        context.put(GOCD_AGENT_IMAGE, "gocd/gocd-agent-alpine-3.19");
+        context.put(LATEST_VERSION, "v23.5.0");
         return context;
     }
 }