Bump mariadb-java-client from 2.1.2 to 2.5.4

Bumps [mariadb-java-client](https://github.com/mariadb-corporation/mariadb-connector-j) from 2.1.2 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@2.1.2...2.5.4)

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

core/build.gradle

@@ -12,7 +12,7 @@ dependencies {
     implementation ('com.google.code.gson:gson:2.6.2')
 
 //    compile group: 'mysql', name: 'mysql-connector-java', version: '8.0.17'
-    implementation 'org.mariadb.jdbc:mariadb-java-client:2.1.2'
+    implementation 'org.mariadb.jdbc:mariadb-java-client:2.5.4'
     compile 'com.github.Fernthedev:fern-configmanager:1.1.3' // Check github releases tag for the version.
 
     // 2. Use Guava types in your public API: