rename defaults in config.py with unique prefix

[tsvikas]

          Hi @tsvikas thank you for interest and effort. I tried to reproduce same steps, and cache files were deleted as expected. Yes it would be good to rename all defaults in `config.py` with unique prefix, I will create an issue for it. Given that, I'll pass on this, but thanks for the effort! 🍰

Originally posted by @TheR1D in https://github.com/TheR1D/shell_gpt/issues/437#issuecomment-1890251144

[tsvikas]

the idea is to change the default cache_path to be /tmp/sgpt_cache, to prevent collision with other apps