Modernize deps

[lcaiffa]

I'm opening this PR to modernize the project's dependencies. Specifically, I updated the paho-mqtt version to address the breaking changes related to the migration to version 2. At that point, I also updated the robotframework version. I ran all the tests as directed and verified that they all passed. To make the tests green, I had to modify the mosquitto configuration, which in the meantime had modified some of its policies for security reasons.