Bump pulsar-client from 2.3.0 to 2.3.1 in /modules/pulsar

Bumps [pulsar-client](https://github.com/apache/pulsar) from 2.3.0 to 2.3.1.
- [Release notes](https://github.com/apache/pulsar/releases)
- [Commits](apache/pulsar@v2.3.0...v2.3.1)

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

modules/pulsar/build.gradle

@@ -3,6 +3,6 @@ description = "Testcontainers :: Pulsar"
 dependencies {
     compile project(':testcontainers')
 
-    testCompile group: 'org.apache.pulsar', name: 'pulsar-client', version: '2.3.0'
+    testCompile group: 'org.apache.pulsar', name: 'pulsar-client', version: '2.3.1'
     testCompile group: 'org.assertj', name: 'assertj-core', version: '3.12.2'
 }