This issue contains comments from PR #2893 (#2893).

Comments

1. The PR adds PostgreSQL 18 to the test matrix
2. Removes Ubuntu 20.04 from the OS matrix
3. Updates the PostgreSQL repository setup
4. Sets fixed port usage for PostgreSQL in the CI workflow
5. Uses APT pinning for the PostgreSQL repository
6. Updates the installation steps for PostgreSQL

Original PR Summary

The pull request titled 'Fix ubuntu ci and start testing PG18' addresses updates to the continuous integration (CI) setup for Ubuntu in the pgrouting project. The changes include adding PostgreSQL 18 to the testing matrix, ensuring that the PostgreSQL installation is clean by purging old versions so that the new installation uses the default port 5432. The update removes support for Ubuntu 20.04, as it is no longer available. Additionally, the repository configuration is updated to use the apt.postgresql.org testing repository to enable testing of PG18. The pull request also replaces the deprecated apt key method for repository certification with the newer trustpg approach.

See the original PR for more details: #2893