[Backport 1.8.latest] Drop support for Python 3.8#1124

mikealfare merged 2 commits into1.8.latestdbt-labs/dbt-spark:1.8.latestfrom

backport/1.8.latest/drop-py38-supportdbt-labs/dbt-spark:backport/1.8.latest/drop-py38-supportCopy head branch name to clipboard