[deps]: Bump org.testcontainers:postgresql from 1.19.0 to 1.20.3

Bumps [org.testcontainers:postgresql](https://github.com/testcontainers/testcontainers-java) from 1.19.0 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@1.19.0...1.20.3)

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

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

build.gradle

@@ -22,7 +22,7 @@ ext {
     openApiVersion = "2.6.0"
     logbookVersion = "2.16.0"
     logstashEncoderVersion = "7.4"
-    postgresContainerVersion = "1.19.0"
+    postgresContainerVersion = "1.20.3"
 }
 
 subprojects { ->