fix: samples/client/petstore/java/vertx-no-nullable/pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-IONETTY-12485149
- https://snyk.io/vuln/SNYK-JAVA-IONETTY-12485150
- https://snyk.io/vuln/SNYK-JAVA-IONETTY-12485151

Author: snyk-bot

samples/client/petstore/java/vertx-no-nullable/pom.xml

@@ -264,7 +264,7 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <vertx-version>3.5.2</vertx-version>
+        <vertx-version>4.5.21</vertx-version>
         <jackson-version>2.17.1</jackson-version>
         <jackson-databind>2.17.1</jackson-databind>
         <jackson-databind-nullable-version>0.2.6</jackson-databind-nullable-version>