build(deps): bump mysql-connector-java in /gateway-server

Bumps [mysql-connector-java](https://github.com/mysql/mysql-connector-j) from 8.0.16 to 8.0.28.
- [Release notes](https://github.com/mysql/mysql-connector-j/releases)
- [Changelog](https://github.com/mysql/mysql-connector-j/blob/release/8.0/CHANGES)
- [Commits](mysql/mysql-connector-j@8.0.16...8.0.28)

---
updated-dependencies:
- dependency-name: mysql:mysql-connector-java
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

gateway-server/pom.xml

@@ -127,7 +127,7 @@
         <dependency>
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
-            <version>8.0.16</version>
+            <version>8.0.28</version>
         </dependency>
         <!--result-->
         <dependency>