fix: samples/client/echo_api/java/okhttp-gson-user-defined-templates/pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMFASTERXMLJACKSONCORE-10500754
- https://snyk.io/vuln/SNYK-JAVA-COMFASTERXMLJACKSONCORE-7569538
- https://snyk.io/vuln/SNYK-JAVA-ORGJETBRAINSKOTLIN-2393744

Author: snyk-bot

samples/client/echo_api/java/okhttp-gson-user-defined-templates/pom.xml

@@ -329,10 +329,10 @@
         <maven.compiler.source>${java.version}</maven.compiler.source>
         <maven.compiler.target>${java.version}</maven.compiler.target>
         <gson-fire-version>1.9.0</gson-fire-version>
-        <okhttp-version>4.12.0</okhttp-version>
+        <okhttp-version>5.0.0</okhttp-version>
         <gson-version>2.10.1</gson-version>
         <commons-lang3-version>3.17.0</commons-lang3-version>
-        <jackson-databind-nullable-version>0.2.6</jackson-databind-nullable-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>
         <junit-version>5.10.3</junit-version>