Bump org.testcontainers:testcontainers-bom from 1.20.5 to 1.20.6 (#3003)

Bumps [org.testcontainers:testcontainers-bom](https://github.com/testcontainers/testcontainers-java) from 1.20.5 to 1.20.6.
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](https://github.com/testcontainers/testcontainers-java/compare/1.20.5...1.20.6)

---
updated-dependencies:
- dependency-name: org.testcontainers:testcontainers-bom
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

build.gradle

@@ -66,7 +66,7 @@ ext {
 	springDataVersion = '2025.1.0-SNAPSHOT'
 	springRetryVersion = '2.0.11'
 	springVersion = '7.0.0-SNAPSHOT'
-	testcontainersVersion = '1.20.5'
+	testcontainersVersion = '1.20.6'
 
 	javaProjects = subprojects - project(':spring-amqp-bom')
 }