Fail to parse OpenAI api response

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I'm using keybert to run some topic modeling tasks and it's very powerful. However, I did have to make some changes to the source code to make the code working flawlessly. Here is my code:

```
import openai
from keybert.llm import OpenAI
from keybert import KeyLLM, KeyBERT

# Create your LLM
client = openai.OpenAI(api_key="sk-XXXXXXXXX")
llm = OpenAI(client, prompt=CUSTOM_PROMPT)

# Load it in KeyLLM
kw_model = KeyBERT(llm=llm)

# Extract keywords
keywords = kw_model.extract_keywords(documents)
```

which throws the following error:

`AttributeError: 'CompletionChoice' object has no attribute 'message'`

Here below a snippet of the traceback:

I believe OpenAI response changed over time and my working work-around is to replace:

`keywords = response.choices[0].message.content.strip()`

with

`keywords = response.choices[0].text.strip()`

in file keybert/llm/_openai.py at lines `181` and `189`

Start by reading keybert/llm/_openai.py around lines 181 and 189, then reproduce the reported Python call with the OpenAI client and inspect the response choice type. The issue is done when the OpenAI response is parsed without the reported AttributeError and keyword extraction completes successfully.

Written by the indexing model from the issue text.