Bump gson in /ocpp-v1_6-example/json-client-implementation

Bumps [gson](https://github.com/google/gson) from 2.8.8 to 2.8.9.
- [Release notes](https://github.com/google/gson/releases)
- [Changelog](https://github.com/google/gson/blob/master/CHANGELOG.md)
- [Commits](google/gson@gson-parent-2.8.8...gson-parent-2.8.9)

---
updated-dependencies:
- dependency-name: com.google.code.gson:gson
  dependency-type: direct:production
...

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Author: dependabot[bot]

ocpp-v1_6-example/json-client-implementation/pom.xml

@@ -41,7 +41,7 @@
 		<dependency>
 			<groupId>com.google.code.gson</groupId>
 			<artifactId>gson</artifactId>
-			<version>2.8.8</version>
+			<version>2.8.9</version>
 		</dependency>
 		<dependency>
 			<groupId>eu.chargetime.ocpp</groupId>