Update aiosmtplib to 5.1.0

[pyup-bot]

This PR updates aiosmtplib from 3.0.2 to 5.1.0.

Changelog

5.1.0

-----

- Feature: Add XOAUTH2 authentication support

5.0.0

-----

- **BREAKING**: Drop Python 3.9 support

4.0.2

-----

- Bugfix: correct aexit signature to comply with async context manager protocol
(thanks oliverlambson)

4.0.1

-----

- Bugfix: Always clear the connect lock on connection lost, allowing client reconnect

4.0.0

-----

- **BREAKING**: Drop Python 3.8 support
- Bugfix: Run `socket.getfqdn` in thread to avoid blocking event loop
if `local_hostname` not provided (thanks Raidzin)
- Bugfix: Clear connect lock on connection lost, allowing client reconnect
- Bugfix: Allow socket connections to use TLS by providing `hostname` and
`use_tls=True`

Links

• PyPI: https://pypi.org/project/aiosmtplib
• Changelog: https://data.safetycli.com/changelogs/aiosmtplib/