devel/py-sarge: Update to 0.1.5

Highlights of the update:

• Improved errors
• Fixed compatibility with Python 3.7 (async is now a keyword)
• Updated tutorial example on progress monitoring

PR: 233298
Submitted by: Mattias Lindvall <mattias.lindvall@gmail.com>
Reviewed by: koobs (ports)
Approved by: koobs (ports), kevans (maintainer)