Bump mariadb-java-client from 2.5.3 to 2.5.4 in /modules/mariadb (testcontainers#2298)

Bumps [mariadb-java-client](https://github.com/mariadb-corporation/mariadb-connector-j) from 2.5.3 to 2.5.4.
- [Release notes](https://github.com/mariadb-corporation/mariadb-connector-j/releases)
- [Changelog](https://github.com/mariadb-corporation/mariadb-connector-j/blob/master/CHANGELOG.md)
- [Commits](mariadb-corporation/mariadb-connector-j@2.5.3...2.5.4)

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

Author: dependabot-preview[bot]

modules/mariadb/build.gradle

@@ -3,7 +3,7 @@ description = "Testcontainers :: JDBC :: MariaDB"
 dependencies {
     compile project(':jdbc')
 
-    testCompile 'org.mariadb.jdbc:mariadb-java-client:2.5.3'
+    testCompile 'org.mariadb.jdbc:mariadb-java-client:2.5.4'
     testCompile 'com.zaxxer:HikariCP-java6:2.3.13'
     testCompile 'commons-dbutils:commons-dbutils:1.7'
     testCompile 'org.apache.tomcat:tomcat-jdbc:9.0.30'