Upstream does not include NEWS in the tarball, but on
the web it is possible to find the following:
v1.5.0 - 2019-10-30
===================
* 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
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