Bump org.elasticsearch.client:transport in /modules/elasticsearch

Bumps [org.elasticsearch.client:transport](https://github.com/elastic/elasticsearch) from 7.17.17 to 7.17.21.
- [Release notes](https://github.com/elastic/elasticsearch/releases)
- [Changelog](https://github.com/elastic/elasticsearch/blob/main/CHANGELOG.md)
- [Commits](elastic/elasticsearch@v7.17.17...v7.17.21)

---
updated-dependencies:
- dependency-name: org.elasticsearch.client:transport
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

modules/elasticsearch/build.gradle

@@ -3,6 +3,6 @@ description = "Testcontainers :: elasticsearch"
 dependencies {
     api project(':testcontainers')
     testImplementation "org.elasticsearch.client:elasticsearch-rest-client:8.13.4"
-    testImplementation "org.elasticsearch.client:transport:7.17.17"
+    testImplementation "org.elasticsearch.client:transport:7.17.21"
     testImplementation 'org.assertj:assertj-core:3.25.3'
 }