Add Python 3.12 to list of supported Python versions

[VersusFacit]

resolves #716

Problem

Adding Python 3.12 should pass a series of tests

• pytest tests/unit local
• pytest tests/functional local
• dbt seed && dbt run in a local jaffle shop using plain pip install dbt-redshift with 3.12 active
• smoke testing run using test-bundle on snowflake against the jaffle-shop-base scenario with 3.12.3 active
• GHA workflow involving integration tests
• release workflow still works

Solution

No code changes beyond GHA workflows and setup.py are needed for this adapter.

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-redshift contributing guide.

[VersusFacit]

Here's the release workflow test build :D https://github.com/dbt-labs/dbt-redshift/actions/runs/10065835355

[VersusFacit]

Additional integration test that gets us 3.12 tested too :D

https://github.com/dbt-labs/dbt-redshift/actions/runs/10067053821