Log levels defaults to DEBUG. Would it be possible to make the Logs levels configurable?

[gdluca]

I could not find a parameter to adjust or turn off Logs (halloy.log file). As a workaround I am running RUST_LOG=ERROR halloy and it seems to work well. There are some really old IRC servers (so not really halloy's fault) that sometimes generate lots of WARN (tls related) and having the possibility to turn off logs per servers completely would be helpful.

Thank you for your amazing work!