fix: samples/client/echo_api/java/native/pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMFASTERXMLJACKSONCORE-15365924

Author: snyk-bot

samples/client/echo_api/java/native/pom.xml

@@ -253,7 +253,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.source>11</maven.compiler.source>
         <maven.compiler.target>11</maven.compiler.target>
-        <jackson-version>2.19.2</jackson-version>
+        <jackson-version>2.21.1</jackson-version>
         <jackson-databind-nullable-version>0.2.7</jackson-databind-nullable-version>
         <jakarta-annotation-version>1.3.5</jakarta-annotation-version>
         <beanvalidation-version>2.0.2</beanvalidation-version>