net-im/py-slackeventsapi: Add py-slackeventsapi 3.0.1

The Slack Events Adapter is a Python-based solution to receive and parse events
from Slack's Events API. This library uses an event emitter framework to allow
you to easily process Slack events by simply attaching functions to event
listeners.

This adapter enhances and simplifies Slack's Events API by incorporating useful
best practices, patterns, and opportunities to abstract out common tasks.