bump dbt-common min to 1.6

[MichelleArk]

resolves #271

docs dbt-labs/docs.getdbt.com/# N/A

Problem

#260 requires dbt-common 1.6 contracts, so we should bump the min dbt-common version for dbt-adapters

Solution

update pyproject.toml

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 contributing guide.

[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 contributing guide.