Python 3.8 support, dependency updates

Changes

This is a maintenance release, there are no feature changes.

• Make it easier to update dependencies (and align requirements.txt and Pipfile.lock)
• Support Python 3.8
• Integrate Renovate

Initial stable release

Features

• Manage GitLab project topics ("tags")
• List GitLab projects (e.g. by topics)
• Manage group memberships (e.g. set permissions on project groups)

Supported Python versions: 3.6, 3.7