Bump r2dbc-mariadb from 0.8.2-alpha2 to 0.8.3-beta1 in /modules/mariadb (#3036)

Bumps [r2dbc-mariadb](https://github.com/mariadb-corporation/mariadb-connector-r2dbc) from 0.8.2-alpha2 to 0.8.3-beta1.
- [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)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Richard North <[email protected]>

Author: dependabot[bot]

modules/mariadb/build.gradle

@@ -7,11 +7,11 @@ dependencies {
     compile project(':jdbc')
 
     compileOnly project(':r2dbc')
-    compileOnly 'org.mariadb:r2dbc-mariadb:0.8.2-alpha2'
+    compileOnly 'org.mariadb:r2dbc-mariadb:0.8.3-beta1'
 
     testCompile project(':jdbc-test')
     testCompile 'org.mariadb.jdbc:mariadb-java-client:2.6.2'
 
     testCompile testFixtures(project(':r2dbc'))
-    testCompile 'org.mariadb:r2dbc-mariadb:0.8.1-alpha1'
+    testCompile 'org.mariadb:r2dbc-mariadb:0.8.3-beta1'
 }