Bump org.mariadb:r2dbc-mariadb from 1.0.2 to 1.0.3 in /modules/mariadb

Bumps [org.mariadb:r2dbc-mariadb](https://github.com/mariadb-corporation/mariadb-connector-r2dbc) from 1.0.2 to 1.0.3.
- [Release notes](https://github.com/mariadb-corporation/mariadb-connector-r2dbc/releases)
- [Changelog](https://github.com/mariadb-corporation/mariadb-connector-r2dbc/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mariadb-corporation/mariadb-connector-r2dbc/commits)

---
updated-dependencies:
- dependency-name: org.mariadb:r2dbc-mariadb
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

modules/mariadb/build.gradle

@@ -13,5 +13,5 @@ dependencies {
     testImplementation 'org.mariadb.jdbc:mariadb-java-client:3.1.2'
 
     testImplementation testFixtures(project(':r2dbc'))
-    testImplementation 'org.mariadb:r2dbc-mariadb:1.0.2'
+    testImplementation 'org.mariadb:r2dbc-mariadb:1.0.3'
 }