net-mgmt/py-ncclient: Update to 0.6.6

Changelog:

• Read ssh timeout from config file if not specified in method call
• Tox support
• Huge XML tree parser support
• Adding optional bind address to connect

https://github.com/ncclient/ncclient/releases/tag/v0.6.6

PR: 238247
Submitted by: Sergey Akhmatov <sergey@akhmatov.ru> (maintainer)