First two logged lines output to stderr instead of stdout

[tiagolascasas]

The first two logged lines when running Clava are output to stderr instead of stdout:

Oct 06, 2025 7:19:24 PM pt.up.fe.specs.util.logging.TagLogger log
INFO: Current major Linux version is 6, only up to version 5.0 has been tested, running at your own risk

This causes some annoyance when mixing Clava with other scripts where we want it to run silently. I don't see a reason to output this as an error, particularly at level INFO, and stdout should be used instead.

Furthermore, is the Linux kernel version warning at all warranted?

[lm-sousa]

I don't see why we would even have a maximum supported version of the Linux kernel. Nor a minimum version...
@joaobispo Any comment?