add a Dockerfile

[d3287t328]

Chatgpt-4 created all of this.

[knrd1]

Thank you for your work, I appreciate! I will review and get back to you.

[raoel]

Some remarks (I did not make the PR and am not owner of this repo)

• Why would you open a port? that's only necessary for traffic TO the bot, not FROM the bot
• use CMD [ "/usr/local/bin/python3", "-u", "chatgpt.py" ] as the last line, without the "-u" it will buffer all logs to output until it finishes, which basically means you will not get logs until you kill the container, which is very inconvenient.

(my Dockerfile is almost exactly the same, except no open port - and works fine)

Good call to add a requirements.txt!