Protocol update to 3.4

[aleksandrs-ledovskis]

There recently was a new PR merged in vertica-python that bumped wire protocol support to v3.4 and added a bunch of comments and descriptions.

As you may know or not, vertica-python is now officially supported and developed by Vertica. So, any changes made there are "official" in a sense that implementation follows protocol to the letter, as obviously they have access to Vertica DB source code.

This fact is specifically underlined in an announcement blog post

In particular, we expect that this Python client will eventually serve as a complete reference implementation of the Vertica client protocol.

I suggest we plan or even start a definitive "3.4" milestone and crosscheck implementation with Python adapter.

[wvanbergen]

I am no longer actively working on Vertica infrastructure, which makes working on this a challenge for me. I'd be happy to accept PRs to move us to the new protocol version though. Because of that, we should make sure we can run integration tests against a Vertica instance that supports this protocol version. This used to be painful in the past but might be easier these days.