deps: update dependency com.google.code.gson:gson to v2.8.8 (#529)

Author: renovate-bot

pom.xml

@@ -170,7 +170,7 @@
     <threetenbp.version>1.5.1</threetenbp.version>
     <objenesis.version>2.6</objenesis.version>
     <errorprone.version>2.9.0</errorprone.version>
-    <gson.version>2.8.7</gson.version>
+    <gson.version>2.8.8</gson.version>
   </properties>
 
   <dependencyManagement>