Bump org.testcontainers:testcontainers from 1.15.1 to 1.21.0 (#299)

Bumps [org.testcontainers:testcontainers](https://github.com/testcontainers/testcontainers-java) from 1.15.1 to 1.21.0.
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.15.1...1.21.0)

---
updated-dependencies:
- dependency-name: org.testcontainers:testcontainers
  dependency-version: 1.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

build.gradle

@@ -67,7 +67,7 @@ dependencies {
 		exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
 	}
 
-    testImplementation "org.testcontainers:testcontainers:1.15.1"
+    testImplementation "org.testcontainers:testcontainers:1.21.0"
     testImplementation group: 'org.awaitility', name: 'awaitility', version: '4.0.3'
     testImplementation("org.assertj:assertj-core:3.27.3")
 }