[LAZY CONSENSUS] Add Apprise Provider

[utkarsh sharma <ut...@gmail.com>]

Hey everyone,

As per the policies for accepting new providers(
https://github.com/apache/airflow/pull/30657) I would like to propose a
LAZY CONSENSUS on accepting the Apprise Provider as a new community managed
provider.

I have raised a PR for the same -
https://github.com/apache/airflow/pull/31533(pending reviews).

Adding Apprise as a provider will help with the notifier feature(
https://airflow.apache.org/docs/apache-airflow/2.6.0/howto/notifications.html)
which currently requires us to have a provider of the recipient service to
send the notification. However, with the addition of Apprise Provider, we
no longer need to add providers for apprise-supported services. The
complete list of supported services can be accessed here -
https://github.com/caronc/apprise#supported-notifications

* Apprise is open-source software - https://github.com/caronc/apprise with
BSD License (BSD)
* Well maintained and documented with over 8.1K starts

If there are no objections, I would request committers to review/merge the
PR.

Thanks,
Utkarsh Sharma