Avoid displaying KeyboardInterrupt exception on terminal if user arbitrarily interrupts the inference

[felladrin]

Currently, if the user interrupts the inference via Ctrl/Cmd + C, it displays the following in the terminal:

Traceback (most recent call last):
  File "test.py", line 18, in <module>
    for output in minigpt4_chatbot.generate(
  File "minigpt4_library.py", line 646, in generate
    token = self.library.minigpt4_end_chat(self.ctx, self.n_threads, temp, top_k, top_p, tfs_z, typical_p, repeat_last_n, repeat_penalty, alpha_presence, alpha_frequency, mirostat, mirostat_tau, mirostat_eta, penalize_nl)
  File "minigpt4_library.py", line 419, in minigpt4_end_chat
    self.panic_if_error(self.library.minigpt4_end_chat(ctx.ptr, ctypes.pointer(token), n_threads, temp, top_k, top_p, tfs_z, typical_p, repeat_last_n, repeat_penalty, alpha_presence, alpha_frequency, mirostat, mirostat_tau, mirostat_eta, penalize_nl))
KeyboardInterrupt

Changes on this PR prevent the exception from being displayed if the user arbitrarily interrupts the inference, stopping the inference process cleanly.

[Maknee]

LGTM. Thanks for the catch -- it's pretty common for people to interrupt chat and I've done that before often.