Flask-opsgenie

Following changes are made in this new release with minor version upgrade

- Add capability to override alert priority
- Add capability for adding extra_props which is a dict and gets included in final alert details.

User facing changes
- Support http.HTTPStatus enums

Non user facing changes just for mention
- test, build and release will now be via github actions.

- Adds alerting feature for async gevent tasks for which flask request does not wait before returning
- Useful for handling unhandled/unknown exceptions created by fire and foreget gevent tasks.

- Remove teardown handler for implicit exception handling, because flask provides error handler for the same purpose from which flask-opsgenie mthod can be called
- Add a manual exception raise function for end user use. This can be used to raise alert for handled exceptions in flask app.
- Update READMD.md

- Bugfix : Add responder to exception alerts
- Feature : Add traceback to exception alerts