Delete Postgres image if running on CI

[andyundso]

We run into space problem on CI when running the tests for newer Postgres version with the new Debian image. This PR amends the tests to delete the Postgres images when running on CI.

[justinclift]

Looks ok to me, lets try it out. 😄

[justinclift]

Awesome, looks like it worked!

I'll update the README here about it in a few hours, and the similar info on the Docker repo as well. 😄

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This is really good stuff @andyundso. Pretty sure lots of people who weren't previously able to auto-upgrade their databases now can do so. 😄

[justinclift]

Uh oh, it looks like we're still running out of disk space:

https://github.com/pgautoupgrade/docker-pgautoupgrade/actions/runs/10094729660

Anyone have ideas on what else we can do to get this working?

[andyundso]

it looks like the runner ran out of disk space when trying to build / push the final image version. not sure if we can delete all these Redash images / containers / volumes after the test to solve the issue.

[justinclift]

k. We'll probably need to put some time aside to experiment. Alternatively, we might need use self-hosted runners for a while (hopefully short term) as with those we can allocate as much disk space as we need.