Feature mute stream log for info level

[azurewtl]

Features
see issue : #1109
llm stream_response alway been print regardless of debug flag
I modified logs.py rather than config2.py.
This is because log is been set via define_log_level rather than config.yaml
To keep things simple, a global variable _print_level is introduced in logs.py

Influence
define_log_level(print_level="INFO") will mute log_llm_stream

[shenchucheng]

@azurewtl Thanks for your improvements. It works when I call define_log_level(print_level="DEBUG") in my Python script entry if I want to print the LLM stream log. However, I'm considering whether to provide a simpler way to set it up, perhaps by passing environment variables METAGPT_LOG_PRINT_LEVEL and METAGPT_LOG_FILE_LEVEL?

[azurewtl]

@azurewtl Thanks for your improvements. It works when I call define_log_level(print_level="DEBUG") in my Python script entry if I want to print the LLM stream log. However, I'm considering whether to provide a simpler way to set it up, perhaps by passing environment variables METAGPT_LOG_PRINT_LEVEL and METAGPT_LOG_FILE_LEVEL?

I thought about using config. however, my proposal is that debug flag should be pass via command line tools.
Oftentimes, If we want to see debug info during development, I run program and pass debug flag such as:

python run.py --debug

Maybe YAML better off storage config that is NOT changed on ad-hoc basis. Otherwise if I want to show less or more info, I need to change config frequently.

[geekan]

@shenchucheng I think this is a new requirement and can be discussed additionally. This PR can be merged first
@azurewtl If there are new changes, submit another PR

[geekan]

DEBUG should be used for default _print_level?

[geekan]

Anyway, I’ll merge first