Bump paho-mqtt from 1.5.1 to 1.6.1

Bumps [paho-mqtt](https://github.com/eclipse/paho.mqtt.python) from 1.5.1 to 1.6.1.
- [Release notes](https://github.com/eclipse/paho.mqtt.python/releases)
- [Changelog](https://github.com/eclipse/paho.mqtt.python/blob/master/ChangeLog.txt)
- [Commits](https://github.com/eclipse/paho.mqtt.python/compare/v1.5.1...v1.6.1)

---
updated-dependencies:
- dependency-name: paho-mqtt
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1,3 +1,3 @@
 amcrest==1.9.3
-paho-mqtt==1.5.1
+paho-mqtt==1.6.1
 python-slugify==5.0.2