Bump mysql-connector-java from 8.0.17 to 8.0.18 in /modules/mys… (#1968)

Bumps [mysql-connector-java](https://github.com/mysql/mysql-connector-j) from 8.0.17 to 8.0.18.
- [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/commits)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Co-authored-by: null <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

modules/mysql/build.gradle

@@ -3,7 +3,7 @@ description = "Testcontainers :: JDBC :: MySQL"
 dependencies {
     compile project(':jdbc')
 
-    testCompile 'mysql:mysql-connector-java:8.0.17'
+    testCompile 'mysql:mysql-connector-java:8.0.18'
     testCompile 'com.zaxxer:HikariCP-java6:2.3.13'
     testCompile 'org.apache.tomcat:tomcat-jdbc:9.0.26'
     testCompile 'commons-dbutils:commons-dbutils:1.7'