Add support for python 3.12

[mikealfare]

resolves #17

Problem

Add support for Python 3.12

Solution

Tasks

Preview Give feedback

1. bump everything to 3.12 where it's currently 3.11
2. run CI from this branch to pick up the new matrix values and make sure things pass
3. verify that dbt-postgres builds successfully for 3.12
4. update any docs that need updating

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the dbt-postgres contributing guide.

[mikealfare]

CI run against this branch using this branch's workflows: https://github.com/dbt-labs/dbt-postgres/actions/runs/10190141128

[mikealfare]

Test release run against this branch using this branch's workflows: https://github.com/dbt-labs/dbt-postgres/actions/runs/10190259358

[mikealfare]

The PyPI release failed on the attached run due to not being able to download the artifact. However, this occurred after the artifact was built and tested, and the GitHub release was successful.