Update Paho MQTT C find package

[uilianries]

Specify library name and version: paho-mqtt-c/1.3.0

From https://github.com/eclipse/paho.mqtt.cpp/blob/e6c96220f8ba239a4e47620be32d76515f6252c0/cmake/FindPahoMqttC.cmake

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the
  conan-center hook activated.

[conan-center-bot]

All green in build 1 (e6625f34f6b93b3aa391bbe1ed46f48529e6a0e5)! 😊

• paho-mqtt-c/1.3.0: Generated 82 packages. All logs here

[Croydon]

This might be correct, but I want to point out that you linked to the C++ repo instead of the C repo. The C repo doesn't seem to have a FindCMake file at all 🤔

[uilianries]

Exactly, because they don't provide one. But both paho-mqtt-c and paho-mqtt-cpp are provided by the same organization.