Fix CreateEmbeddingResponse object type

[davidmigloz]

The current object is set embedding but the API returns list instead.

Example:

curl https://api.openai.com/v1/embeddings \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "input": "The food was delicious and the waiter...",
    "model": "text-embedding-ada-002",
    "encoding_format": "float"
  }'

Response:

{
  "object": "list",
  "data": [
    {
      "object": "embedding",
      "index": 0,
      "embedding": [ 0.0022579778, ...]
    }
  ],
  "model": "text-embedding-ada-002-v2",
  "usage": {
    "prompt_tokens": 8,
    "total_tokens": 8
  }
}

cc @schnerd

[schnerd]

Thank you!