Bump java-client from 2.7.14 to 2.7.15 in /modules/couchbase

Bumps [java-client](https://github.com/couchbase/couchbase-java-client) from 2.7.14 to 2.7.15.
- [Release notes](https://github.com/couchbase/couchbase-java-client/releases)
- [Commits](couchbase/couchbase-java-client@2.7.14...2.7.15)

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

modules/couchbase/build.gradle

@@ -3,5 +3,5 @@ description = "Testcontainers :: Couchbase"
 dependencies {
     compile project(':testcontainers')
 
-    testCompile 'com.couchbase.client:java-client:2.7.14'
+    testCompile 'com.couchbase.client:java-client:2.7.15'
 }