Bump org.testcontainers:postgresql from 1.18.0 to 1.20.6

Bumps [org.testcontainers:postgresql](https://github.com/testcontainers/testcontainers-java) from 1.18.0 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](testcontainers/testcontainers-java@1.18.0...1.20.6)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pom.xml

@@ -67,7 +67,7 @@
     <picocli.version>4.7.6</picocli.version>
     <flink.version>1.19.2</flink.version>
     <postgres.version>42.5.0</postgres.version>
-    <testcontainers.version>1.18.0</testcontainers.version>
+    <testcontainers.version>1.20.6</testcontainers.version>
   </properties>
 
   <dependencyManagement>