Use log level warning only for real warning

[Spacetown]

How would this feature be useful?

If the python logger is configured to handle warnings in a special wa, e.g. to format them to be recognised by a CI pipeline execution, the following messages are cached as warnings but they are more like a info:

1. The log entry if the session is started: nox > Running session lint
2. The log entry if multiple sessions are executed: nox > Ran multiple sessions:

Describe the solution you'd like

There are several ways to solve the issue:

1. Change the log function to use info. This would change the colour.
2. Add a new log level SESSION_INFO like it's done for SUCCESS. Here the color can be configured

Describe alternatives you've considered

Ignore warnings issued by nox depending on the message text.
I think this is not a nice solution.

Anything else?

I tested solution 2 in my fork and it worked very well.