GPT-4o support

[akurou]

GPT-4o support is not working properly.
Reason: tiktoken encoding needs to be updated for GPT-4o.

Currently encoding = tiktoken.get_encoding("gpt-3.5-turbo") is used (openai_helper.py row 656).
You need to change tokenizer to "p50k_base" to fix an error.

[VaMPIRESqq]

hi, I found a solution to our problem, change line 656 to:

encoding = tiktoken.get_encoding("p50k_base")

don't forget about the tabulation rules