fix: samples/client/petstore/java/rest-assured-jackson/pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-ORGAPACHECOMMONS-10734078

Author: snyk-bot

samples/client/petstore/java/rest-assured-jackson/pom.xml

@@ -277,7 +277,7 @@
     </dependencies>
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <rest-assured.version>5.3.2</rest-assured.version>
+        <rest-assured.version>5.5.6</rest-assured.version>
         <gson-version>2.10.1</gson-version>
         <gson-fire-version>1.9.0</gson-fire-version>
         <jackson-version>2.17.1</jackson-version>