Bump mysql-connector-java from 5.1.6 to 8.0.16

Bumps [mysql-connector-java](https://github.com/mysql/mysql-connector-j) from 5.1.6 to 8.0.16.
- [Release notes](https://github.com/mysql/mysql-connector-j/releases)
- [Changelog](https://github.com/mysql/mysql-connector-j/blob/release/8.0/CHANGES)
- [Commits](https://github.com/mysql/mysql-connector-j/compare/5.1.6...8.0.16)
Signed-off-by: Ndependabot[bot] <support@github.com>

pom.xml

@@ -20,7 +20,7 @@
     <spring.version>5.0.2.RELEASE</spring.version>
     <slf4j.version>1.6.6</slf4j.version>
     <log4j.version>1.2.12</log4j.version>
-    <mysql.version>5.1.6</mysql.version>
+    <mysql.version>8.0.16</mysql.version>
     <mybatis.version>3.4.5</mybatis.version>
   </properties>