update postgres version to 15 in integration test

[jimexist]

integration test suite is now run against postgres 15 - the latest version

Which issue does this PR close?

Closes #.

Rationale for this change

What changes are included in this PR?

Are there any user-facing changes?

[alamb]

🤔
https://github.com/apache/arrow-datafusion/actions/runs/3247313443/jobs/5327261887

  /usr/bin/docker pull postgres:15
  Error response from daemon: manifest for postgres:15 not found: manifest unknown: manifest unknown
  Warning: Docker pull failed with exit code 1, back off 1.267 seconds before retry.
  /usr/bin/docker pull postgres:15
  Error response from daemon: manifest for postgres:15 not found: manifest unknown: manifest unknown
  Warning: Docker pull failed with exit code 1, back off 8.932 seconds before retry.
  /usr/bin/docker pull postgres:15
  Error response from daemon: manifest for postgres:15 not found: manifest unknown: manifest unknown
  Error: Docker pull failed with exit code 1

[alamb]

Marking as draft to signify it needs some work prior to review

[alamb]

https://github.com/apache/arrow-datafusion/actions/runs/3279444796/jobs/5399275992

👍

Thanks @jimexist