Update to armbian stable v20.08 (Caple) Bump to new stable armbian [version 20.08](https://github.com/armbian/build/releases/tag/v20.08)

New boards:

• Added orange PI Pc

Notice: This will is the last release using python2 next releases will migrate to python3

Builder:

• Improved compilation VM speed
• Parametric virtualenv (preparation for python3)
• Fix citrico-config to hide kilipper if not installed
• Automation of releases

##Upstream versions:

• Armbian: 20.08.4
• OctoPi: 0.17.0