Added Radxa Rock 5 Support, Performance Improvements, and Bug Fixes

This release includes the following changes:

• Update Readme: Requires Python 3.7 #254 by @cstenkamp
• Added Siemens Simatic IOT2000 Gateway to detect.py #255 by @schnurma
• Fix Libre AML_S905X_CC LePotato not being detected as Linux #257 by @makermelissa
• Add support for Radxa Rock 5 #258 by @happyme531
• Lazily evaluate conditions #201 by @CamDavidsonPilon

To use in CPython, pip3 install Adafruit-PlatformDetect.

Read the docs for info on how to use it.