What are you trying to do?

I'm writing integration tests for a Python project (https://github.com/f18m/ha-alarm-raspy2mqtt) that publishes messages to an MQTT broker.
I would like to use testcontainers to create the integration tests and noticed that there is no specialization available for MQTT and for its most-used broker which is Mosquitto.
So I'd like to propose the addition of a MosquittoContainer class to testcontainers-python.

Why should it be done this way?

There are a number of helpers that could be provided out of the box to ease integration testing of MQTT applications.

I can provide a PR to add my own MosquittoContainer implementation if there is interest by the project maintainers...