fix: pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMGOOGLEOAUTHCLIENT-575276

Author: snyk-bot

pom.xml

@@ -71,7 +71,7 @@
         <dependency>
             <groupId>com.google.oauth-client</groupId>
             <artifactId>google-oauth-client</artifactId>
-            <version>1.20.0</version>
+            <version>1.31.0</version>
         </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>