rbintegrations 2.x had an uncapped dependency on asana, which made it

difficult to install on Python 2.7, as Asana 3.x no longer supports

Python 2.7.
This change adds a cap to the dependency on 2.7, and bumps up the

minimum version to 3.x on Python 3.

Unit tests passed on Python 2.7 and 3.6-3.10.
Verified the version of asana used in each of those versions.