Version 0.6.0

[aminalaee]

Changelog:

• Change extra installations to specific drivers #436
• Fix query result named access #448
• Fix connections getting into a bad state when a task is cancelled #457
• Revert #328 parallel transactions #472
• Drop Python 3.6 #458
• Add _mapping property to the result set interface. #447
• Fix query result named access #448
• Change extra installations to specific drivers #436

[collerek]

I like to mark which changes are breaking in case of (major) version bump, but I see that it was not the case for databases so we can keep it as it is, still consistent with what it used to be.