Migrate to environment variables for ThingSpeak API keys

[utkarsh867]

Reference to

botmlcode/report/thingspeak.py

Line 7 in 31fe84c

# topic = "channels/"+ config.CHANNEL_ID +"/publish/"+ config.API_KEY

It is not feasible to store the API key on Clearbot, even as a python file.

The way forward could be to add it to the environment as an environment variable, or be able to fetch it on the go.

Personally, I prefer to just use environment variables at the current stage.