Bump mysql-connector-java in /modules/junit-jupiter

Bumps [mysql-connector-java](https://github.com/mysql/mysql-connector-j) from 8.0.14 to 8.0.15.
- [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@8.0.14...8.0.15)

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

Author: dependabot-support

modules/junit-jupiter/build.gradle

@@ -10,7 +10,7 @@ dependencies {
     testCompile 'redis.clients:jedis:3.0.1'
 
     testRuntime 'org.postgresql:postgresql:42.2.5'
-    testRuntime 'mysql:mysql-connector-java:8.0.14'
+    testRuntime 'mysql:mysql-connector-java:8.0.15'
     testRuntime 'org.junit.jupiter:junit-jupiter-engine:5.3.2'
 }