Warning not to use Mono even when that is the default build config for Renode

[shareefj]

The following warning is emitted by pyrenode3 when using it, WARNING:root:Using mono with Renode built from sources might not work correctly., but Mono is the default dependency listed in the Renode installation instructions. Can you fix this inconsistency and/or describe how it should be built for usage with pyrenode3.

Relevant docs: https://renode.readthedocs.io/en/latest/advanced/building_from_sources.html

[sean-anderson-seco]

This warning is especially annoying since it's printed with logging.warning and not warnings.warn, so it can't be suppressed via normal means. When running tests in parallel this results in dozens of lines of noise.