Add groq completion example

[sklinkert]

Add usage example for groq

groq offers the same API like OpenAPI

#797

PR Checklist

• Read the Contributing documentation.
• Read the Code of conduct documentation.
• Name your Pull Request title clearly, concisely, and prefixed with the name of the primarily affected package you changed according to Good commit messages (such as memory: add interfaces for X, Y or util: add whizzbang helpers).
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. Fixes #123).
• Describes the source of new concepts.
• References existing implementations as appropriate.
• Contains test coverage for new functions.
• Passes all golangci-lint checks.

[sklinkert]

@devalexandre thanks for approving it :)

@tmc can you merge it?

[ImPedro29]

Using GenerateContent method this implementation doesn't work completely. The request model of completions is different to openai defaults. Mine json request:

{
   "model":"llama3-70b-8192",
   "messages":[
      {
         "role":"system",
         "content":[
            {
               "text":"some text...",
               "type":"text"
            },
            {
               "text":"some text...",
               "type":"text"
            }
         ]
      },
      {
         "role":"user",
         "content":[
            {
               "text":"hi",
               "type":"text"
            }
         ]
      }
   ],
   "temperature":0,
   "max_tokens":300
}

Response:

API returned unexpected status code: 400: 'messages.0' : for 'role:system' the following must be satisfied[('messages.0.content' : value must be a string)]

[sklinkert]

@ImPedro29 Have you tried it with the latest version of langchaingo? I had the same error but it worked for me after upgrading it.

[ImPedro29]

I updated and after some corrections to my embed engine, the same errors are appearing:
Using version v0.1.9

Error local:

langchaingo/llms/openai/internal/openaiclient/chat.go

Line 338 in 3bb95e1

r, err := c.httpClient.Do(req)

POST https://api.groq.com/openai/v1/chat/completions
Body in my message above

It looks like groq doesn't support the same models that openai gpt supports... Maybe in a future groq update it could be

Edit: I just tested GenerateContent method