Bump gson from 2.2.4 to 2.8.9 in /visualizer-service-rest-frontend#147

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dependabot/maven/visualizer-service-rest-frontend/com.google.code.gson-gson-2.8.9ApolloDev/apollo:dependabot/maven/visualizer-service-rest-frontend/com.google.code.gson-gson-2.8.9Copy head branch name to clipboard