Added test case to verify TLS 1.3 auto-negotiation support

[sharmagot]

This MR adds a new integration test to verify that the Vertica Python client correctly supports TLS 1.3 negotiation.

The test validates that the client can successfully connect using TLS 1.3 when supported by the server.

If the server only supports TLS 1.2, the connection should gracefully fall back to it.

The test also logs the negotiated TLS version for debugging and verification purposes.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

root seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}