Add PostgreSQL 18 Support

[modrink]

This commit updates the build scripts and configuration to make PostgreSQL 18 the default “latest” version:

• docker-bake.hcl
  • Updated the default targets list to include debian-17/alpine-17 and removed older -16 as latest
  • Changed BASETAG for debian-latest and alpine-latest to 18 and added corresponding 18 tags
  • Added explicit debian-17 and alpine-17 targets to preserve PostgreSQL 17 support
• generate-docker-bake.sh
  • Bumped MAIN_TAG from 17 to 18
  • Updated TAGS_EXTRA to include 17 so previous versions remain supported

These changes ensure that running ./generate-docker-bake.sh now generates a docker-bake.hcl where latest images point to PostgreSQL 18, while still maintaining backward compatibility with versions 13–17.

https://www.postgresql.org/about/news/postgresql-18-released-3142/

[prodrigestivill]

Hello, thanks for the contribution!

I had since yesterday trying to find time to do the same change.
Sorry I didn't see your PR before, but appreciate a lot.

I see your CI test don't work, so I don't expect my patch to work either, because it is the same...

For a long time I wanted to change from bake to custom CI workflow, I will try to do this soon to be able to release the 18 image...

[prodrigestivill]

Direct publish (without test) worked... as said I have to fix this tests...

I close this PR, thanks anyway.