Enable autocommit

[perttus]

Some of the macros are not committing changes (e.g. update table statements) since the autocommit is disabled by default
Could we change it to True. I suppose it would be enough to add it to

dbt-vertica/dbt/adapters/vertica/connections.py

Line 85 in f0eca51

conn_info = {

It could be also se with parameter in the dbt profile.