build(deps): Bump testcontainersVersion in /promotion-notifier-backend

Bumps `testcontainersVersion` from 1.19.8 to 1.20.1.

Updates `org.testcontainers:rabbitmq` from 1.19.8 to 1.20.1
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.19.8...1.20.1)

Updates `org.testcontainers:spock` from 1.19.8 to 1.20.1
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.19.8...1.20.1)

Updates `org.testcontainers:postgresql` from 1.19.8 to 1.20.1
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.19.8...1.20.1)

Updates `org.testcontainers:elasticsearch` from 1.19.8 to 1.20.1
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.19.8...1.20.1)

Updates `org.testcontainers:testcontainers` from 1.19.8 to 1.20.1
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.19.8...1.20.1)

Updates `org.testcontainers:selenium` from 1.19.8 to 1.20.1
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.19.8...1.20.1)

---
updated-dependencies:
- dependency-name: org.testcontainers:rabbitmq
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.testcontainers:spock
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.testcontainers:postgresql
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.testcontainers:elasticsearch
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.testcontainers:testcontainers
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.testcontainers:selenium
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

promotion-notifier-backend/build.gradle

@@ -7,7 +7,7 @@ buildscript {
         springBootVersion = '3.3.2'
         springDepenedcyMgmtVersion = '1.1.6'
         springCloudVersion = '2023.0.2'
-        testcontainersVersion = '1.19.8'
+        testcontainersVersion = '1.20.1'
         awaitilityVersion = '4.2.0'
         wiremockVersion = '2.35.2'
         baseDockerImage = 'azul/zulu-openjdk:21-latest'