Bump mariadb-java-client from 2.5.3 to 2.5.4 (#5914)

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]

build.gradle

@@ -140,7 +140,7 @@ dependencies {
     antlr4 'org.antlr:antlr4:4.8-1'
     compile 'org.antlr:antlr4-runtime:4.8-1'
 
-    compile group: 'org.mariadb.jdbc', name: 'mariadb-java-client', version: '2.5.3'
+    compile group: 'org.mariadb.jdbc', name: 'mariadb-java-client', version: '2.5.4'
 
     compile 'org.postgresql:postgresql:42.2.9'