Bump mysql-connector-java in /authentication-server (#31)

Author: dependabot[bot]

authentication-server/pom.xml

@@ -43,7 +43,7 @@
       <dependency>
         <groupId>mysql</groupId>
         <artifactId>mysql-connector-java</artifactId>
-        <version>5.1.46</version>
+        <version>8.0.28</version>
       </dependency>
       <dependency>
         <groupId>org.apache.servicecomb.fence</groupId>