Update paho-mqtt to 1.5.1

[pyup-bot]

This PR updates paho-mqtt from 1.4.0 to 1.5.1.

Changelog

1.5.0

===================

* Add support for clean_session on subscribe helper. Closes 219
* Add support for non-standard bridge connection. Closes 282
* Fix hang with QoS 2 message and clean_session = False. The fix replace hang
with message DROP. See README for known limitation. Closes 284 and 286
* Fix connection establishement timeout. Closes 291 and 288
* Add support for connecting through a proxy. Closes 315
* Add MQTT v5 support. Closes 334
* Improve error message when sending queue is full. Closes 378
* Improve error handling during initialization on edge case. Closes 387 and 388
* Allow to specify local client port used (similar to bind_address). Closes 390
* Add method is_connected to know if MQTT connection is established. Closes 414
* Set connection timeout to keepalive. Closes 425

Links

• PyPI: https://pypi.org/project/paho-mqtt
• Changelog: https://pyup.io/changelogs/paho-mqtt/
• Homepage: http://eclipse.org/paho