Update minimum Python version to 3.8 #192
Description
Background
Currently the minimum version is set to Python 3.6. However, Python 3.6 is already EOL, and many packages stopped support for it.
Acceptance Criteria
- Update minimum Python version to 3.6 in Poetry
- Update Docker-Start-Container to Ubuntu 20.04 and update to Python 3.8 (https://github.com/exasol/integration-test-docker-environment/blob/main/starter_scripts/Dockerfile)
- Update Docker-Test-Container to Ubuntu 20.04 and update to Python 3.8 (https://github.com/exasol/integration-test-docker-environment/blob/main/tests/Dockerfile)