[change] Releaser: remove chatGPT integration (obsolete)

[nemesifier]

Now that we have added the change-log bot, the chatGPT revision of the change log in the releaser tool is obsolete, an AFAIK it has also never worked nor for me or @pandafy.

Therefore, we can safely remove this.

[openwisp-companion]

This issue has been automatically assigned to @BHARATH0153 who opened PR #661 to address it. 🎯