fix: pom.xml to reduce vulnerabilities (#1535)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMGOOGLECODEGSON-1730327

Author: snyk-bot

pom.xml

@@ -77,7 +77,7 @@
     <okhttp3.version>4.9.2</okhttp3.version>
     <guava.version>30.1.1-jre</guava.version>
     <googlehttpclient.version>1.40.1</googlehttpclient.version>
-    <gson.version>2.8.8</gson.version>
+    <gson.version>2.8.9</gson.version>
     <slf4j.version>1.7.32</slf4j.version>
     <bouncy.version>1.69</bouncy.version>
     <json.version>20210307</json.version>