Worked on upgrading the embedded PostgreSQL test environment to version 15.x within the hhru/nuts-and-bolts repository, focusing on enhancing compatibility and maintainability for Java-based testing workflows. The upgrade involved updating the default PostgreSQL image and revising the changelog to document the transition from version 13.x to 15.x. Additionally, guidance was added to the testing documentation to assist developers in verifying driver compatibility with the new database version. The work leveraged configuration management skills and required proficiency in both Java and YAML, ensuring that the test infrastructure remained robust and up-to-date for ongoing development and integration processes.