Bump org.testcontainers:testcontainers-bom (#9592)

Bumps the development-dependencies group with 1 update: [org.testcontainers:testcontainers-bom](https://github.com/testcontainers/testcontainers-java).


Updates `org.testcontainers:testcontainers-bom` from 1.20.2 to 1.20.3
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.20.2...1.20.3)

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

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

Author: dependabot[bot]

Diff for: build.gradle

@@ -116,7 +116,7 @@ ext {
     springSecurityVersion = '6.4.0-SNAPSHOT'
     springVersion = '6.2.0-SNAPSHOT'
     springWsVersion = '4.0.11'
-    testcontainersVersion = '1.20.2'
+    testcontainersVersion = '1.20.3'
     tomcatVersion = '10.1.31'
     xmlUnitVersion = '2.10.0'
     xstreamVersion = '1.4.20'